Reminds me of being present when a Captain RN, who was a former SSN CO, met a fairly elderly FGN Captain at Kiel in the 1980s, and comment on the fact that the Herr Kapitan had no medal ribbons.
The Herr Kapitan was quiet for a few moments and, on being asked why he had made no response, replied that he had been quickly counting the number of U-boats he had served in, or commanded, prior to VE-Day. He must have been very fortunate indeed since the answer was six and, no, the Captain RN asked no more questhtions.
On a more prosaic level, I believe I am correct in saying that serving personnel in the FGR forces were banned from wearing medals or campaign stars awarded by the Nazis.
Jack