Latvia 1919 Sc. 49-50? With Expertizing Marks?

Hi,

I got these stamps in a lot, and I noticed they appear to have expertizing marks on the back.

I assume that is because they appear to be Sc. 49-51 (no watermark and appears to be thin (pelure I guess?) paper) with a 2017 Classic Specialized Catalogue value of $9.5, $9.5, and $21.

Does anyone know who the expertizing mark is for? I tried doing some research, but have been unable to find it so far. It looks like the mark says "FJ.", but there isn't a bar on the top of the "J"....

They are owners handstamps.

OK, thanks for the information. That's disappointing.....I suppose the marks would be considered faults then?

In this case, since the marks were applied to pelure paper and show from the front, most collectors would considered them to be undesirable.