maybe you should try eating at once, if you dont feel anything with one, double it, whats the worst that could happen, you'll throw up, then it would be like you ate one good cookie, and you will get something instead of 2 nothings. or nothing happened. in which case, id get your money back.

thats the bad thing about edibles, you cant really tell if they are real all the time or not, even if there is plant material in there, it's hard to tell what is weed and what isnt sometimes even when you see it.