WWII French Forgery Or Weak Strike?

I came across these two stamps in my collection. The one on the right matches every catalog image I've seen.

As you can see the one on the left clearly lacks the details. Is this a forgery or a genuine weakly struck stamp?

I'm very much interested in this too. I have quite a few of this issue and find that a number of them look, well, just different. I've noticed 3 distinct shades, and of course Scott's only lists 1.

My Michel catalog gives me two shades, a 'rosakarmin' from Dec. 17, 1941 and a 'dunkelrotbraun' from Feb. 14, 1942.

Yvert et Tellier, lists two different stamps: rose (#516) and "brun-rouge", brown-red (#517).
My very old (1953) S&G lists two stamps: brown and red.

Well now that opens a lot of interesting possibilities.....and leaves me scratching my head. I'd be interested in hearing other opinions on this

The Maury Specialized (French) catalog says that the Resistance counterfeited this stamp, but they appear to be about perf 12 instead of perf 14. The Intelligence Service also counterfeited this stamp, and about a dozen other definitives of the same time period, but I can't tell the distinguishing marks, nor read the lengthy French explanation.

The Resistance fakes are very cheap, the Intelligence Service's range from cheap to very expensive, expertizing required, of course.

Here's something that will hopefully 'awe' everyone: http://1f50bersier.free.fr/
(a word of warning - you do need to read French fluently, or use Google Translate to read the contents of this website).

To date I have not found a better resource for this stamp.

Great link Scb ! To have the information pertaining to this stamp, click on "Les faux" from the list on the left.

thanks SCB

That link is great...thank you for pointing it out. Never would have found that one on my own!

based on the link above I'm beginning to believe that the one on the left is indeed a forgery, specifically the IS. Anyone have a grading/authentication service they recommend?

Not a forgery for me :)