Sick on mdma come up

So I got some 300mg pills (tested) and I took one and after about 40 minutes I was rolling then was sick now I’ve been told I should have split the pill so it’s not as strong but I redosed at 600mg double dropping now I know that that is stupid and I’ve learned my lesson as I can’t remember a single thing after redosing but why wasn’t I sick when I redosed especially at 600mg and when I was sick after 5 mins everything calmed down really quick and back to feeling good I’m not overly bothered about being sick because after about 5 mins I’m back to feeling good but just curious