Hungarian 1919 Issue With Printing On Back Of Stamp?

The Hungarian 1919 "Issues of the Kingdom" is overprinted as above to commemorate the Romanian withdrawal. According to Scott, the overprint reads "Entry of the National Army-November 16, 1919".

There is a note to indicate forged overprints exist.




But turning over the stamps, all of them -save one- (Scott 306-310) have this printing on the back in different colors. Only the 5f green in my collection has no printing on the back.

Marque Garantie SOC MIS

???????

Scott makes no mention of this.

Was this to guarantee their genuineness?

Are these "official" markings?

Or are they private?

And,is this a mark of a genuine - or forged overprint stamp?

Purely a guess but I think they're expertizer markings.

Thanks to Mr. Jay Carrigan.

The response I received with the same question in 2007....

Its listed as an expertising mark here: http://www.filatelia.fi/experts/namesm.html

My guess would be "SOC MIS" indicates the expert (e.g., individual or society) and "marque garantie" that its genuine.

Wow, thanks for the specific answer Rod222!

There must have been a lot of remainders that ended up in collections, as I have found these marks on the stamp issues in several different feeder albums.

HungaryforStamps, thanks for the link. Clearly, it is nicely listed. It is interesting that this "Social Mission Society" only has markings on this remaindered overprint issue.