^ Yes, cause they are useless. However, since the pills you got from a big time dealer, i doubt that a couple of pills would matter to him, if anything your ass will be pressured into giving out names.
So all all, its better not to say anything to protect your friends, and yourself. Put it this way, your not lying to the dealer cause he never asked if you know who's stole em.
Furthermore this dealer deserves to be robbed, fucking selling PMA pills off as MDMA. I know if i brought pills from a dealer, and they were PMA i would do something about it, esp if it fucked up my night, or injured myself or others. Since this is a drug reduction form and not a fight forum, we should beat up dealers selling PMA.