The Clones have done this Assignment and all of it aith Melitus, yes- that should be obvious, as bAzrael points out, because as Mleitus says, you havew all been mixed up, so some of you have been doing that already. Everyone has been thrpough the same experiences since you woke up on the sofa at the start of the Assignment.
Rade- well done for identifying the fact this this is a bit of a problem. Sadly, I can hardly start advancing solutions to you; that is up to you. That is, of course, one of the central dilemmas of the piece. Ideally, though, your final submission would remove this as a problem.
Azrael, did you think the idea was to trick your other half into drinking? If you both advance the same argument, it should, really, be for the SAME person to drink, not both of you asking the other (though this is possible with some philosophies), assuming your logic is identical. Regardless, don't burn your brain out worrying about that; right now you are only playing one person, so advance an argument based on that and we shall see what transpires.
But yes, obviously, if your argument is simply "I think you should drink because I want to live" then you would just get that thrown back at you.