Hi, I have did this by configuring multiple ldapUserDirectory tags and multiple server tag in default-ldap-users-directory-bundle.xml file as shown below. also you can find attatchment of this file.

<?xml version="1.0"?>
<component name="org.nuxeo.ecm.directory.ldap.storage.users">
  <implementation class="org.nuxeo.ecm.directory.ldap.LDAPDirectoryDescriptor" />
  <implementation class="org.nuxeo.ecm.directory.ldap.LDAPServerDescriptor" />
  <require>org.nuxeo.ecm.directory.ldap.LDAPDirectoryFactory</require>
  <!-- the groups SQL directories are required to make this bundle work -->
  <require>org.nuxeo.ecm.directory.sql.storage</require>
  <require>org.nuxeo.ecm.platform.usermanager.UserManagerImpl</require>
  <extension target="org.nuxeo.ecm.directory.ldap.LDAPDirectoryFactory"
    point="servers">

    <!-- Configuration of a server connection
      A single server declaration can point to a cluster of replicated
      servers (using OpenLDAP's slapd + sluprd for instance). To leverage
      such a cluster and improve availability, please provide one
      <ldapUrl/> tag for each replica of the cluster.
    -->
    <server name="default">
      <ldapUrl>ldap://server1:389</ldapUrl>
      <!-- Optional servers from the same cluster for failover
        and load balancing:
        <ldapUrl>ldap://server2:389</ldapUrl>
        <ldapUrl>ldaps://server3:389</ldapUrl>
        "ldaps" means TLS/SSL connection.
      -->
      <!-- Credentials used by Nuxeo5 to browse the directory, create
        and modify entries.
        Only the authentication of users (bind) use the credentials entered
        through the login form if any.
      -->
       <bindDn>cn=unotech,cn=users,dc=unotechsoft,dc=com</bindDn>
      <bindPassword>redhat@123</bindPassword>
      <!-- Attempts to get a result when LDAP is temporary unavailable -->
      <retries>5</retries>
    </server>
    <server name="default1">
      <ldapUrl>ldap://server2:389</ldapUrl>
      <bindDn>cn=Manager,dc=hitendra,dc=com </bindDn>
      <bindPassword>secret</bindPassword>
      <retries>5</retries>
    </server>
  </extension>
  <extension target="org.nuxeo.ecm.directory.ldap.LDAPDirectoryFactory"
    point="directories">
    <directory name="ldapUserDirectory">
      <server>default</server>
      <schema>user</schema>
      <idField>username</idField>
      <passwordField>password</passwordField>
      <searchBaseDn>dc=unotechsoft,dc=com</searchBaseDn>
      <searchClass>person</searchClass>
      <!-- To additionally restricte entries you can add an
        arbitrary search filter such as the following:
        Beware that "&" writes "&" in XML.
        <searchFilter>(&(sn=toto*)(myCustomAttribute=somevalue))</searchFilter>
      -->
      <!-- use subtree if the people branch is nested -->
      <searchScope>subtree</searchScope>
      <!-- using 'subany', search will match *toto*. use 'subfinal' to
        match *toto and 'subinitial' to match toto*. subinitial is the
        default  behaviour-->
      <substringMatchType>subinitial</substringMatchType>
      <readOnly>true</readOnly>
      <!-- comment <cache* /> tags to disable the cache -->
      <cacheEntryName>ldap-user-entry-cache</cacheEntryName>
      <cacheEntryWithoutReferencesName>ldap-user-entry-cache-without-references</cacheEntryWithoutReferencesName>

      <!--
           If the id field is not returned by the search, we set it with the searched entry, probably the login.
           Before setting it, you can change its case. Accepted values are 'lower' and 'upper',
           anything else will not change the case.
      -->
      <missingIdFieldCase>lower</missingIdFieldCase>

      <!-- Maximum number of entries returned by the search -->
      <querySizeLimit>200</querySizeLimit>

      <!-- Time to wait for a search to finish. 0 to wait indefinitely -->
      <queryTimeLimit>0</queryTimeLimit>

      <creationBaseDn>ou=people,dc=example,dc=com</creationBaseDn>
      <creationClass>top</creationClass>
      <creationClass>person</creationClass>
      <creationClass>organizationalPerson</creationClass>
      <creationClass>inetOrgPerson</creationClass>

      <rdnAttribute>sAMAccountName</rdnAttribute>
      <fieldMapping name="username">givenName</fieldMapping>
      <fieldMapping name="password">userPassword</fieldMapping>
      <fieldMapping name="firstName">givenName</fieldMapping>
      <fieldMapping name="lastName">sn</fieldMapping>
      <fieldMapping name="company">o</fieldMapping>
      <fieldMapping name="email">mail</fieldMapping>

      <references>
        <inverseReference field="groups" directory="sqlGroupDirectory"
          dualReferenceField="members" />
      </references>

    </directory>

    <directory name="ldapUserDirectory1">
      <server>default1</server>
      <schema>user</schema>
      <idField>username</idField>
      <passwordField>password</passwordField>

      <searchBaseDn>dc=hitendra,dc=com</searchBaseDn>
      <searchClass>person</searchClass>

      <!-- use subtree if the people branch is nested -->
      <searchScope>subtree</searchScope>

      <!-- using 'subany', search will match *toto*. use 'subfinal' to
        match *toto and 'subinitial' to match toto*. subinitial is the
        default  behaviour-->
      <substringMatchType>subinitial</substringMatchType>

      <readOnly>true</readOnly>

      <!-- comment <cache* /> tags to disable the cache -->
      <cacheEntryName>ldap-user-entry-cache</cacheEntryName>
      <cacheEntryWithoutReferencesName>ldap-user-entry-cache-without-references</cacheEntryWithoutReferencesName>

        <missingIdFieldCase>lower</missingIdFieldCase>

      <!-- Maximum number of entries returned by the search -->
      <querySizeLimit>20</querySizeLimit>

      <!-- Time to wait for a search to finish. 0 to wait indefinitely -->
      <queryTimeLimit>0</queryTimeLimit>

      <creationBaseDn>ou=people,dc=example,dc=com</creationBaseDn>
      <creationClass>top</creationClass>
      <creationClass>person</creationClass>
      <creationClass>organizationalPerson</creationClass>
      <creationClass>inetOrgPerson</creationClass>

      <rdnAttribute>cn</rdnAttribute>
      <fieldMapping name="username">uid</fieldMapping>
      <fieldMapping name="password">userPassword</fieldMapping>
      <fieldMapping name="firstName">cn</fieldMapping>
      <fieldMapping name="lastName">sn</fieldMapping>
      <fieldMapping name="company">o</fieldMapping>
      <fieldMapping name="email">mail</fieldMapping>

      <references>
        <inverseReference field="groups" directory="sqlGroupDirectory"
          dualReferenceField="members" />
      </references>

    </directory>

  </extension>

  <implementation class="org.nuxeo.ecm.directory.sql.SQLDirectoryDescriptor" />
  <require>org.nuxeo.ecm.directory.sql.SQLDirectoryFactory</require>

  <extension target="org.nuxeo.ecm.directory.sql.SQLDirectoryFactory"
    point="directories">

    <directory name="sqlUserDirectory">

      <schema>user</schema>

      <dataSource>jdbc/nxsqldirectory</dataSource>

      <table>users</table>
      <idField>username</idField>
      <passwordField>password</passwordField>
      <passwordHashAlgorithm>SSHA</passwordHashAlgorithm>
      <autoincrementIdField>false</autoincrementIdField>
      <computeMultiTenantId>false</computeMultiTenantId>
      <dataFile>users.csv</dataFile>
      <createTablePolicy>on_missing_columns</createTablePolicy>
      <querySizeLimit>50</querySizeLimit>

      <cacheEntryName>sql-user-entry-cache</cacheEntryName>
      <cacheEntryWithoutReferencesName>sql-user-entry-cache-without-references</cacheEntryWithoutReferencesName>

      <references>
        <inverseReference field="groups" directory="sqlGroupDirectory"
          dualReferenceField="members" />
      </references>

    </directory>
    <directory name="sqlGroupDirectory">

      <schema>group</schema>
      <dataSource>jdbc/nxsqldirectory</dataSource>
      <table>groups</table>
      <idField>groupname</idField>
      <dataFile>groups.csv</dataFile>
      <createTablePolicy>on_missing_columns</createTablePolicy>
      <autoincrementIdField>false</autoincrementIdField>

      <cacheEntryName>sql-group-entry-cache</cacheEntryName>
      <cacheEntryWithoutReferencesName>sql-group-entry-cache-without-references</cacheEntryWithoutReferencesName>

      <references>
        <tableReference field="members" directory="multiUserDirectory"
          table="user2group" sourceColumn="groupId" targetColumn="userId" schema="user2group" 
          dataFile="user2group.csv" />
        <tableReference field="subGroups" directory="sqlGroupDirectory"
          table="group2group" sourceColumn="parentGroupId" 
          targetColumn="childGroupId" schema="group2group" />
        <inverseReference field="parentGroups" directory="sqlGroupDirectory"
          dualReferenceField="subGroups" />
      </references>

    </directory>
  </extension>

  <extension
    target="org.nuxeo.ecm.directory.multi.MultiDirectoryFactory"
    point="directories">
    <directory name="multiUserDirectory">
      <schema>user</schema>
      <idField>username</idField>
      <passwordField>password</passwordField>

      <source name="userSQLsource" creation="true">
        <subDirectory name="sqlUserDirectory" />
      </source>
    <source name="userLDAPsource">
        <subDirectory name="ldapUserDirectory" />
      </source> 
       <source name="userLDAPsource">
        <subDirectory name="ldapUserDirectory1" />
      </source>
    </directory>
    <directory name="multiGroupDirectory">
      <schema>group</schema>
      <idField>groupname</idField>
      <source name="groupSQLsource" creation="true">
        <subDirectory name="sqlGroupDirectory" />
      </source>
      <source name="groupLDAPsource">
        <subDirectory name="ldapGroupDirectory" />
      </source>
    </directory>
  </extension>
  <extension target="org.nuxeo.ecm.platform.usermanager.UserService" point="userManager">
    <userManager>
      <userCacheName>default-cache</userCacheName>
      <defaultAdministratorId>unotech</defaultAdministratorId>
      <defaultGroup>members</defaultGroup>
      <users>
        <directory>multiUserDirectory</directory>
        <virtualUser id="unotech" searchable="false">
          <password>redhat@123</password>
          <property name="firstName"></property>
          <property name="lastName"></property>
          <group>administrators</group>
        </virtualUser>
        <anonymousUser id="Guest">
          <property name="firstName">Guest</property>
          <property name="lastName">User</property>
        </anonymousUser>
      </users>
      <groups>
        <directory>sqlGroupDirectory</directory>
      </groups>
    </userManager>
  </extension>
</component>