Interesting...the only armed aircraft that I can think of, that used Argus engines would be either the Fw189 (but it was armed with 7.92 MG15 weapons) or the Ar96, which only had one 7.92 MG17.
There is one other consideration, and that would be the early Hs129. It was powered by two Argus As410 engines and armed with two 7.92 MG17 plus two 20mm MG151/20 cannon.
Quite odd, really, since the MG131 ammunition is in the mix.
Is it possible that you may have a dumpsite instead of a crash site?
For example, at a Luftwaffe base, they tossed a great deal of items as well as many aircraft were destroyed where they sat during bombing & strafing attacks.
After the war, many Luftwaffe aircraft were lumped together, crushed and buried if they weren't scrapped out for recycling.