The subject behavior will occur when the NTFRS service detects a name conflict.
This can occur if you manually create a folder on multiple computers in the replica set before the folder has been able to replicate, or if you improperly perform an authoritative restore and NTFRS is running on the other members of the replica set when the restored NTFRS starts.
NTFRS manages files and folders by their unique GUID. The file name or folder name is simply a property of the file system object. When NTFRS detects an object with the same name but a different GUID, it renames one of the objects.
NOTE: DO NOT delete any of these objects and rename others. This will cause more naming conflicts. After replication is complete, you can rename the object you wish to keep and delete the others.