One of those trigger plates is of the 'old style' without the added support screw. I wonder which 3 Model 1893s are no longer in existance. The size difference may be due to the way the bolts are positioned, along with camera angle, etc. Also, check out the 'hammer cocking ramp' on the far right bolt. That must be old style, too.
I'd guess there's multiple lower tangs, but unless the seller says there are multiple bolts, I wouldn't know if it's the same one shot 3 ways, or 3 different ones. better email questions before bidding, and get an inventory!