Depends too on the ladies' rules on the same condom being used to penetrate both of them. A lot of duo partners don't want the same condom used for both of them.
That's interesting - I've only had a duo with a single pair of girls that were close friends and only did duos with each other and wasn't a problem for them so it never occurred to me that it would be an issue.. I never realized it was a concern but can understand why it could be..

