Hello Philippe
First let me welcome you to the forum, it is indeed very dificult to find one of these, I know of only this piece and one other in a collection, have you more information on these as it was from Ulrich's site that I gleaned what little I know,I'd like to ask you about the figure you place on production, is this figure accurate or somebody's best guess, it's just as difficult to find definitive information on these than to find an example. Do you have any other information on these knives, do you know of any other specimens out there apart from yours?.Perhaps you could post some pictures of your example??
I agree with you that it is not very difficult to tell the difference betwen an original and a modern piece, I personally think that Ulrich made them not to fool anybody, each knife I believe is numbered, the originals are not. There are a number of other big differences that are also easy to spot hence my feeling that these were not made to fool anybody with at least a basic knowledge of an original Lippert Waidblatt.

thanks

Gary