I'm going to date 2 people at once without telling them
Why do you want to date them both without telling them?
They exaggerated themselves on their social media for me, then, I'll decide if they're worthy enough or not.
I see why you'd want to be careful about this situation. You should be honest though and tell them what you are doing and how you feel.
They tried to trick me.
That may be so, but that doesn't mean you should reciprocate.