Quite interesting,
The receiver of the 1907 test appears to be set lower into the frame as the #2 (notice the edge above the sideplate).
It appears that the 'later' 45s were constructed using general P08-pattern designs which were slightly modified, probably to ease production.
The 'early' 45s, (like the 45-carabine?), appear to be of a more experimental, fully handmade design.
This would make the 'later' pattern a good candidate for determining a machine setup for a production line (as for the initially intended 200 test pieces).
IMHO, it makes #2 a very unlikely US-tested candidate, but rather a .45 DWM production test pattern (tool room) version.
At least I believe there is good proof of 2 distinct original .45 luger patterns.
This got me thinking again.
Pictured below are the rough frame forging and the finished P08 frame.
You can see that the forging is a good deal larger than the finished frame would be. To my surprise, it would be feasible to create the 1907 frame with it's 55 degree angle from a P08 forging. Creating the #2 frame from this forging does not appear to be possible...