What would you do if you found out that you were dating an identical twin?

This would be a hypothetical, if it didn't happen to me lol. When I was in college I was dating a coworker. She was fun, beautiful, but she was busy a lot. At one point I was invited to meet the rest of her family. The person who I thought was my girlfriend greeted me at the door, hair was a bit different, but facial features and every thing else were the same. Hell even body language and expressions. So I did what I'd normally do, I hugged and kissed her. She had an odd look on her face but I guess I ignored it. And then I go to the dining room to meet everyone else and there sitting is my girlfriend. I'm absolutely fucking confused. The girl I kissed sat next to her and she commented "I can see why you like him so much, fantastic kisser". My face is red, I sit down. I immediately start apologizing, I feel like an absolute piece of shit. I should have paid better attention. The weirdest part is my girlfriend didn't seem to be upset. She told me it was okay, that she saw it as a bit of a joke and funny but made me promise to never kiss her again. We became good friends, and it turns out my girlfriend's sister plays for the other team so umm I'd be barking up the wrong tree anyway. And no, nothing pornographic happened, nothing sexy happened, it was just a weird story.

We ended up parting amicably two years later, but maintained a pen pal kind of friendship. She's a married mother now. And obviously I'm with my wife of 10 years.

In any case it was weird.
What would you do if you found out that you were dating an identical twin?
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