The females are unaware that the exchange has taken place, and may possibly never find out until upon receiving positive results from an STI test.
Note: Even better if the banditry victims are best friends.
'Yeah, slipped it up the fit one first, then her butters mate!'
'Wash your hands in between?'
'Na, i was a right QUIM BANDIT!!'
(possibly ending the conversation with a smell of the quim bandit's fingers)