That's almost always the case with coupons, though. Sure, you can exclude current customers under some coupon schemes, but you risk alienating them... And losing an existing customer is costly, since you put so much into gaining them in the first place.
If you don't like the terms, don't sign up for it. As I said, Groupon isn't magic. Making a bad deal with them will not magically turn into a good deal. You have to use Groupon as a tool, not a genie.
