The duel event just activated in the morning of day 7. Out of nowhere.
I haven't even talked to Evelyn in this playthrough yet.
This bug has been reported before, but unfortunately we have not found a way to fix it.
It seems that it only happens sometimes even when going through the game the exact same way. We've tried to do something to fix it in 1.11 but it wasn't written in the changelog due to simply not being able to know whether it's actually fixed or not.