If you are really trying to figure out what is most commonly mixed with MDMA, ecstasydata.org will give you a good idea.
Piperazines are usually used instead of MDMA, rather than with it. Occasionally pipe/MDMA pills pop up, but it's a waste of expensive MDMA to a chemist to mix it with piperazine and ultimately produce a "ball pill", common additives to MDMA positive pills are usually more universally desirable chemicals, or something common and legal like caffeine.
Piperazines often feel like you're about to roll, but you never do. They can be rather confusing and almost always leave you up all night with some dysphoria, be it mild or severe and frightening.
It's possible you got very low dose pills, it's possible you got any number of RC's. It's not something we can really identify without a reagent test.
We do not allow "what did I take?" threads, or substance speculation/substance ID so I am closing this one up. You can check out pillreports.com to see what it may have been from others who have reagent tested and reported, or check out the common adulterants that are sold as MDMA and determine what you may have got. Only way to know in the future is test-
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