Two Time Capsules with same disk name - Time Machine settings "mix up" targets?
A1: I do believe TM uses UUIDs to identify backup servers. There shouldn't be any issues with duplicate names.

A2: Renaming the disks would probably help you identify it, but it is unlikely that it would solve this problem. As mentioned in A1, TM uses UUIDs to identify disks.

A3: I would try removing the disk through the "Select Disk" button below the disk list (this does not delete your existing backups) and reselecting it.

I would believe that this was likely caused by a graphical glitch.

Good luck.