I may be wrong but I think there may some discrepancies with #1U and #1Y, dates and images. There is a 2014 book ISBN 9781608871858 and a 2018 book ISBN 9781683835226. Both included a comic in the back but the comics look and feel different. I think #1U and #1Y are referencing these comics.
I have the books and comics if more pictures are needed. More information can be found at: New TMNT Variant(s) Discovered ! | TMNT: A Collection
Probably do what I do and throw your hands in the air and scream. LOL
Maybe just acknowledge the dark black one is from the 2014 book and the faded one was from the 2018 book. Here are some photos I tried to take. I need to build me a stand. I sell books and take photos every day but never get it correct.
Here is front and back of 2014.
Here is 2018 front and back.
The only other thing I can think of is one says ashcan. I know of several meaning for ashcan variants, but I always thought they were smaller like both of these comics and printed on newspaper type paper that the 2018 one looks like so you may want to make it the 2018 comic and the 1U the 2014 comic which has 1984 now I guess because it is a reprint and has 1984 on the back. I’ll know which one mine are, so I won’t lose too much sleep over it. I do have another I am investigating some more but will post soon. Thanls for all the work you guys do.
@WDB thanks for the heads-up.
I did some more research and found out both entries have a price ID attached to them with issue related information.
It turns out #1U is the 2018 Insight Editions Ashcan Reprint and #1Y is the 2014 Insight Editions Ashcan Reprint.
I edited the entries just now, using these descriptions.
Probably do what I do and throw your hands in the air and scream. LOL
I’m doing that right now.
Thanls for all the work you guys do.
My pleasure! 
