I agree w/ the last post – lower it a bit. Then you’ll know.
Also, even thought the other offer is higer doesn’t mean it is better. If you have shorter closing times, are more likely to get funded quickly, etc then you may be on top already and they are just trying to get more money out of you. So – even if they aren’t lying, and you see proof of the other offer, they may be tricking you.
Too many houses out there to give in to this kind of stuff, I think.