Portraits and action poses grouped together on T206 sheets?

[steve B]

The "plates" were actually limestone stones, some size x about 4 inches thick. Typically after use they were resurfaced and laid out for some other print job.

I've seen a handful of cards showing a bit of possible carry over between P150 and 350. Those show what I think are remnants of the deeper areas of scratching.
There's a lot of room to study aspects that haven't been looked at. Pat has also made a bunch of progress with other marks that are consistent, and may or may not appear on more than one back. I'd thought that the sheets for different brands would be different, but I think he's proven that isn't always the case, and other than grouping subjects by common features I haven't yet seen much solid proof that different brands had different sheet layouts.

A couple of the areas that could bear a bit of looking into.
Early vs later P150 sheets.
The Magie has some issues with the back on a few positions, which aren't simple damage, because the consistently match small differences on the fronts. (Yes completists, there's at least 6-8 different Magies. ) I haven't seen those faults on the back of any other P150's. Finding them would probably prove to be interesting.

P150 vs P350
Some of the P150 scratches may have been deep enough to still just barely show on P350. If that's what the marks are, the question becomes whether the plate was resurfaced and totally redone with new transfers, and it's just by chance the same one was used Or if only a small portion was redone at first, for instance they removed the 1 and replaced it with a 3 or replaced 350 with 150. That would require checking the position of the numbers relative to the rest of the back to see if any have a slight difference.

Separating the probably three different runs of 150's and 350's. Some cards show some indication that the masters were reworked at least once during each of the 150 and 350 series. It really needs a ton of work, identifying which subjects, and what reworking was done. That would take a lot of detailed scans.
I just finished doing a first draft of something similar for the 49 Leaf, and just hunting up passable scans of obvious differences on a 49 card set took a few days.

Steve B