you probably wouldn't get 50:50, more like 80:20 at the most; the MDMA is basically a decoy.
you may be able to detect PMA if you're very careful. follow the "advanced testing technique" in the chemgen faq, watch everything closely, and assume that *any* green or orange color means PMA. still, a mixture of green and dark blue or purple would be difficult to detect.
TLC will separate the components, and there is a possibility that you may get some separation with chromatography paper, but i'd have to try it. MDMA has a molecular weight about 10% higher than PMA so it's *possible* you might get at least a thin line of green above the liquid front.
someone should try that btw.. i dont have a test kit because i don't *need* one.. but if the method works it's extremely simple.