Exercise caution in your business affairs; for the world is full of trickery.
But let not this blind you to the virtue there is;
The longer I collect stamps, the more forgeries I have

Nothing much surprises me anymore.
Stamp collectors by their very nature are mischievious.
These were probably printed around 1924 -1930 long before
Al Gore invented the internet, so I would say someone
had hold of the plates, so why not print a few more off?
No damage in forging a bogus issue :)
In those days the disemination of information
was a lot slower, and a set of Odessa issues
would be bought by an unknowing lad in lower brixton
when he received his "stamps on approval"
They certainly look pretty.