Help With A Stamp From 1918 - Hungary– Michel No. 220:

1918 / Republic of Hungary – Michel No. 220 – war relief stamps with diagonal overprint.
According to the Michel Catalogue, this stamp is listed as "violet." I have two copies of it; one of them appears more grayish-violet in color.
Is this simply faded, or are there known variants of this stamp listed in other catalogues (I am using the Michel Catalogue)?
Thank you for your help, and Merry Christmas.

The right-hand stamp shows traces of the original colour on the right, so it looks like it has faded. Presumably the ink's an older form of pigment magenta.

Faded stamp.
Also the paper has faded over time.