I did a query at OID end to findout if something wrong there, I used the following query to get his data:
ldapsearch -L -h myserver -p 389 -s sub -b "cn=example,cn=example, dc=example,dc=com" -w password -v "cn=
I got the 2 matches for his account. Which was causing the issue. Now which is active account that we need to findout. I checked with AD administrator which account is active for this user based on OU. So he gave me the output which I used to delete inactive account. And update GUID in FND_USER for this user and it worked.
User was very happy so do I.
Happy Troubleshooting !!!