It is possible that the luger was in it during the war, but far more likely that it was matched up by a GI. A luger fits in it, and many GI's grabbed a holster. In many of the rear area's when weapons were turned in, guns in one pile, holsters in another, magazines in a 3rd and so on.
GI's would pick what they wanted.
Unless you talked to who brought it back, and they remembered right, that is the only way you'd know
Ed