On reconciling the membership of a particular MUC, reconcile any nickname conflicts
Given a temporary communication failure in a cluster, nodes may have been operating and independently offering services to users. When rejoining the cluster there will be reconciliation of MUC participants. As part of this, deal with the case that 2 users could have joined the same MUC with the same nickname.
It may impossible to tell which one really is Spartacus (kick them both?)
One or more may have registered
Any kick may have to be comprehensive - the user could be joined from more than one device.
It might be the same user on both nodes