Comment # 1 on bug 1081469 from Wolfgang Bauer

First of all, there is no "KDE4".
I suppose you are talking about KDE Plasma 5, that's the only KDE desktop we
currently support/ship.

But, logging in to a KDE session twice with the same user is not supported and
doesn't work (since years, even in KDE4 times already).

*** This bug has been marked as a duplicate of bug 1008105 ***