It's just a normal query, one is a znc and the other is normal (external client or same client not on the znc).

1) Open mIRC > connect to ZNC (zncnick)
2) Open KiwiIRC or any other client > normalnick
3) From KiwiIRC /query zncnick blahblah
4) From mIRC > /query normalnick blahblah2
5) Reply back and forth to leave some msgs for the ZNC buffer to load on restart.
6) Close mIRC
7) Open mIRC > connect to ZNC (zncnick)

The ZNC will load the channels in their tabs + ONE TAB for zncnick and ONE TAB for normalnick INSTEAD of ONE UNIQUE TAB for the normal query as it should be.