I set up dates for two girls at about the same time, I'm not sure if one will come so I set up the second.

Problem is, the one i'm unsure of I've already had sex with, and she agreed to meet tomorrow, but she's been shit testing a lot lately and only texted she finished watching GoT after she agreed to hang out and drink tea (she doesn't wanna drink booze). I haven't seen her for more than a week and want to lock her down as a plate.

Second girl is cute and its my first date with her, but sex isn't guaranteed. I'm thinking of flaking on her. Would I ruin my chances with her if I flake? Or is it better to flake on the chick I already smashed?

EDIT: I should mention that I should have another girl coming from out of town on a 4 hr train ride to visit me the next day, so I don't think ill be able to see either girl until weekend if I flake on them.