Well, I just got some in. When I first saw the name, I thought of bkmdma (methylone) but also ketamine. When I have AI analyze its chemical structure, it basically says it's similar to MXE--a more serotonergic Ketamine with longer duration. However, there's a wiki which confirms your suspicions that it's a MDMA/MDA like stimulant. Actually a bit of a let down for me as I need Ketamine-type effects.
If anyone knows of a vendor carrying something other than tilmetamine (DCK, MXPr, 2-fdck, etc) please let me know. I'm super bummed I didn't do more research and trust my intuition.
Somehow I get curious and let myself get sucked into finding answers for this sort of thing. I think I've got an idea what this stuff is but I spent more time than I wanted looking up info and reading about it. Then too much time writing. I think the likely answer is a manufacturer or shipper made a similar mistake as you did and it's something else, a 'different' methl K.
It could be something else but the strongest possibility is that it's bk-methl-k or β-Keto-Methylbenzodioxolylpentanamine. More commonly known as pentylone, a synthetic cathinone. Not one of the more popular ones. Or it's possible they wanted pentylone and the maker made methl k by mistake. It wouldn't be the first time something like this happened.
As soon as I saw this stuff available it didn't make sense to me. Methl k has only been recorded as synthesized once before, 50 years ago. Possibly a few more times for a laugh but there's not much point. The ingredients could be whipped up into at least a dozen other recipes. Stuff that people are familiar with. That are well liked favorites. Or lesser known exotics that are unique and interesting. So why this?
The one recorded bioassay, at 100 mg, doesn't help things. Almost all the other stuff that's active in it's close family would produce a very noticeable to strong to too strong effect at that dosage. There's also close relatives that are bunk. In phikal the tester says, 'It had no effects. I was busy and too wound up and didn't sleep until 3 am, but this was probably unrelated to the methl k.' If it was someone naive to the effects of stims it's could be possible getting wound up and staying up late was an effect, only they were too inexperienced to notice.
That's very unlikely, it's probably Shulginn tasting it. If not him someone from his close circle of experienced psychoknots. Maybe the most experienced drug takers in the world. If they say there were no effects there were no effects, at least anyone would be interested in. Coffee has a noticeable effect no matter how busy or wound up you are.
I was looking at dates and this stuff has been around at least 3 weeks with no description of effects. This makes me suspcious. Pentylone can be felt at 50 mg, a medium dose is 100-200 mg, on up. There's other cathies that are much more potent. If I had some I'd test it with a reagent to find out what it is. Especially if I had a lot. Then I'd find a willing human.
Start very small, to test for allergies and real big fuckups. I recently read the reports of some surivors of the 2cbro mo dragonfly fuck up. It seems that was a turning point in harm reduction. Don't test alone and be careful of body load. This group can cause problems with heart, circulation, and vasoconstriction in an overdose. 100 mg could be safe but there's plenty of stuff that's sensitive at the 1-5 mg level and smaller.
It feels weird writing this, I don't like putting down vendors' magazines. Hopefully I'm wrong and it is Methyl-K and it turns out to be amazing stuff. It's still a possibility. I think I read somewhere it was tested on rodents and they had a great time. They became euphoric and all sang Twist and Shout. I can't find the report now but I'm pretty sure I saw it.
I'm not a chem ist, not an expert, often I"m full of shit. This is all speculation, if you're curious and want to try for the unique opportunity I'd go for it. I'm a little tempted actually. It's an opportunity to try something that's never been tried before in human history. That has a small but real chance of being really special. A smaller chance of being something that changes the world.