Wrong account display

I encountered a very strange issue: I have two account A (Kubuntu 17.10) and B (Funtoo fully updated). The Server is on Centos and v6.2.9-pro. Both the clients and the server are fresh installs.
The upper area of the clients main window shows the account name and with a click on the avatar icon the account menu appears. It seems like, when B shares libraries to A, then the account information on the A computer changes - at least visually - to that of B, i.e. the account name changes to B and also the account menu shows B.
However, since A and B have different passwords, it is still the filelist of A which gets synced.
Does anybody understand my issue and maybe could help to find out what is wrong?

after some more testing, I think this is some kind of bug which is connected to my setup. seafile is integrated in a kolab installation and recieves its user base from the kolab ldap.
The user, which is admin (i.e. the one, which was set up during installation) is also the user which is displayed in the GUI regardless of which actual account information is used.
Also, the directory structure from the admin user is visible in the main window, although not accessible.
After several logout/login cycles, that phenomenon disappears, but the account name changes again back to the admin user.
this is some annoying crap and every help appreciated.