It appears Reese has created a somewhat new frame bracket with this 2 piece welded design.
Now more questions...
Since you now have 2 complete DC kits from different revisions, If you lay just the cam arm and the black yoke on top of each other, no frame plate, are the arms/yokes different? Meaning one has an offset more than the other?
You also seem to have both the older snap up brackets and the new HD snap ups with the added gusset. If you look at the end view of them on the TT frame, does it appear the new HD bracket has the chain hook point where the chain will hang plumb closer to the A frame on the new HD bracket than the older style?
This one pic of yours having HD snap up on 1 side and the older one on the other side "seems" to show the chain would hang closer to the frame on the HD bracket. But this could be a photo illusion.

I have a "hunch" that Reese may have created that new 2 piece DC frame plate to shift the DC more under the frame to get the chain to hang more plumb and closer to the TT frame. I would "think" it would cost more money to make the 2 piece frame plate than the 1 piece. So the change appears to be intentional. They may have been trying to help the problem of bending snap up's with this tweak. It now comes back to the cam arm, if the cam arm and yokes are the same between the 2 vintages you have, then for sure the cam arm is moved under the frame more when using the 2 piece bracket.
The discovery continues...