Is it possible JIDs with only different resources joining same multi-user chat room

Question

In xmpp, following 2 users could join multi-user chat(MUC) or subscribe to same pub-sub node?

public@service.com/user1 public@service.com/user2

Answer 1

When joining an anonymous MUC room, a room where others do not know the "real" JID of others in the room, the connecting user provides their own JID.

When joining a non-anonymous room the users provide their full JID which is transmitted then to all occupants.

In either case there is nothing to prevent the user from joining with the same bare JID but different resources. More details on the MUC protocol, specifically around joining a room can be found in XEP-0045: Basic MUC Protocol.

When subscribing via pub-sub the client can provide either a full JID or a bare JID (no resource) when subscribing. Details for this can be found in the pub-sub XEP, XEP-0060

Answer 2

In most MUC implementations, you must join the room with a different nickname for each of your resources. If you use the same nickname for the second resource, you are likely to get a conflict error.