"Another attribute type is already using the name or OID" error during ldap migration

Issue

• When running the migrate script for 7.1 to 8.2:

  Beginning migration of Directory and Administration servers from /opt/redhat-ds . . . 
  Beginning migration of directory server instances in /opt/redhat-ds . . . 
  Your new DS instance 'slapd-ds1' was successfully created. 
  Could not import the LDIF file '/tmp/nsrootzyffuj.ldif' for the migrated database.  Error: 256.  Output: importing data ... 
  [23/Aug/2010:15:04:46 -0400] dse - The entry cn=schema in file /etc/dirsrv/slapd-ds1/schema/60mozilla.ldif is invalid, error code 20 (Type or value exists) - attribute type nsAIMid: Does not match the OID "1.3.6.1.4.1.13769.2.4". Another attribute type is already using the name or OID. 
  [23/Aug/2010:15:04:46 -0400] dse - Please edit the file to correct the reported problems and then restart the server. 
  
  Exiting . . . 
  Log file is '/tmp/migrateXhsZEb.log'