Is there another room away from the pens they could have a run in separately?
I was going to suggest this. If you're not going to attempt bonding in your front room I don't think it would matter if one started to become territorial, but I would be concerned at anything that might set off feelings of aggression/frustration/irritation between them and I would think that if the one still in the pen can see the other running around that might be the case.
If you're still going to try on Monday and if you feel they need somewhere between now and then to run around then I would remove each from the room one by one.