I think 1/M and 1/T are extras.
I have the cover that looks like 1/U. The barcode on that (70985303326400181) matches 1/T. And the cover artist is Bueckert. That makes me think U and T are the same.
I don’t own it, but the Schmalke cover (1/S) is labeled as the TOSScomics variant and the M is the El Rey.
I found this eBay listing showing the back of the Schmalke cover. It’s a joint exclusive between El Rey and The One Stop Shop (T-O-S-S).
That leads me to think M and S are duplicates.
Thanks!