Recertifying Certifier ID problem- repeated organizational unit

I recently had to recertify a certifier ID that was about to expired so i did the standard procedure on my administrator from configuration tab with the certify option, but now im having a problem with every user that belongs to the Certifier. The certifier is /GTM/CNA/ y recertified it with /CNA but now the users have in their id´s something like John Smith/GTM/GTM/CNA,

and now they cant access their database because the ACL has the old username. their Peoples documents have changed too.

What did i do wrong?

How can i undo it ?

Thanks for your help,