[Koha] Urgent help - Duplicate Title show on OPAC Search

I am using koha 3.0.1 on open suse 11.1 and nozebra. I noticed that koha is dupilcating titles on the OPAC search. The books under each duplicate are the same (same barcode and other marc field). I check the biblio table at the backend on the database (mysql) and find just one instance of the title. I also use the catalogue search I found that only one instance of the record. I rebuild the index by running the ./rebuild_nozebra in the migration_tools and the situation remain the same. Any help will be appreciated. thanks