Problems with multiple levels

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I have a voice chat in one level between two users.
I´ve tried to add a new level with a intro menu before join the level of the voice chat.
It seems that the users will not be in the same room if I have multiple levels: in fact, if I remove that level from the builds they are in the same room (player1, player2) and can have a voice chat. If instead I add a level before they are not in the same room (player1,player1) and can´t have voice chat.
That´s strange and I don´t know why it happens. What can be the cause of that? Conflicts of what?