Cataloging some skins I ran across a duplicate skin but with different materials.txt properties applied to it.
109g14_10, named "9./JG300 by DutchGuy"
and
109g14_13, named "9./JG300 by DutchGuy"
One seems to be crisper along the wing leading edge and the other duller, which makes me think the only difference is how the materials.txt file is applied.
This is also noted on the skins download page. You will see 2 of the same name in the hangar.
Tested offline. Just a heads-up.