T206 Centering Marks? Red on top

[Blitzu]

Hello all, new here but been reading a lot and using the threads on this site for awhile to help me identify various things. I tried searching for this topic but didn't find anything clear on it so sorry if this is a repost or common knowledge.

I've been collecting T206's for a number of years, primarily to put together a complete series of backs.

Anyways, I just recently acquired a very nice raw Piedmont 350, Factory 25 Blackburne. I noticed right away that there were clear marks at the center of the picture box on all four sides. I had never seen these before, or at least stared at any one of my T206's at the front for long enough to notice these. I thought right away there may be an issue with the card. Google searches yielded nothing of help, and I didn't quite know how to phrase the search. These look like centering marks on each side from the printer. The mark on the top is clearly red and the others are grey/black.

I started looking at eBay at other T206's scans of cards with high quality scans/photos and started seeing a trend. Most of the Piedmont 350's have these marks. Some appear to have only one or more marks while others have all four. Some of the top marks appear to be black while others are white. The other consistent factor is the marks appear mostly on the Piedmont 350 factory 25's. Although, I did find these marks on one SC 150 and a Piedmont 150.

Does anyone know anything more about these markings?

I took photos of the card I have and I also made copies of photos taken from eBay of other cards with these marks.

Thanks for the wonderful site.