While the name you gave them did not match, the account number did. So, the other bank knows who actually owns that account.
Contact their BSA Officer and ask him or her for the name(s) and/or discuss mutually registering under 314(b). Having the name will affect your reporting responsibility if you consider them to be your suspect(s)...
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.