This issue is really strange, even the stamps have "low value" they were intensively forged.

In a close observing I can determine three types of forgeries:

1.)
The 20000 (green): The brackets “(“ and “)” does not have a crescent moon shape (both ends are thin, in the middle thick.

2.)
The 1000 (blue): different characters, slanting to each other.

3.)
The 200 (red): different characters, wrong, too thin brackets.

In my example here I overlay a genuine overprint (white) above forged overprint to make the differences visible.

Would like to hear comments, corrections and additional information from other collectors.