Migration Manager for Active Directory

Error 0xe3000004 when merging users

Hello,

I am merging users and match them with a different name  using a import file like this : SAMAccountName  SAMAccountName

some of my users can't be merged and I get this kind of errors:

Error 0xe3000004. Source object matched by the following high-priority matching rule: objectGUID=1D1C0C8B17F61B4CA8AD636E68165D66 has already been matched with another target object by the following low-priority matching rule: objectClass=user

I verified my service attributes and they are all empty on the destination side.

Can someone give me any insights on how to resolve this ?