This is not a bit. Dead serious. There is a luxurious hotel suite for a long weekend with whatever food, treats, toys and equipment you both request.
They are you from another reality where some mundane event is slightly different on the other side of the solar system yet to reach us. They are not a clone or time traveller. Everyone goes back to their own reality at the end. They are you with all of the benefits no complications or ethical questions.
And just in case no they cannot be gender swapped. (Curious why you might ask this? Hmm)
Do you have sex?
You can do other stuff of course if so comment. I love my ace comrades.
There would be a tense standoff where id freak out and may try to subdue and/or kill myself until I can give one of my passphrases to myself i have in case of fae trickery or dopplegangers. Gotta make sure I'm not a skinbeast or pod-person.
After that we probably wouldn't directly fuck each other, but three-way with me, myself and my GF. Which probably still counts as a "Yes" overall.