Second "ghost" slave

I’m trying to update out univention servers. We have two (dc and dc2). When I run univention-upgrade it is complaining that a third computer is lacking the required minimum version for the update. This server (dcbackup) can be found in the UI but there is no IP listed and I am not aware of a third computer.

This third computer is said to run 4.1 while both of my other computers are updated to 4.4. Why am I saying this? Because initially I thought maybe it is kind of an alias.

Can I remove this system (and if so, how), how to gather more information?

Are you sure you have 3 servers listed in the UI?

If you have 2 DCs, the first one installed should be the primary and the second one the backup. At least in any classic setup.

I’m not saying that there is nothing wrong, any further problems reported in system diagnosis?