This situation should be avoided if you and you're friend arent almost
having sex with theese girls on the meetinglocation.
Calculate your chances for everything to go smooth when you game a girl.
What are the odds of a F-close? Only you know that.
Then calculate the chance for your wingman to get it?
Multiply theese numbers and there is the probility for you and your friend
to get laid at the same time.
Either both of you make it, or no one does (unless large amounts of alcohol is involved... or the girls are sexualfreaks

)
Either way both of the girls wanne get laid, or they dont.
But If there is a situaiton like this I definetly aggree with Sprks.
Make some excuse. But for the things your are hoping will happen, there shouldnt be neccesary to make one.