No problem...you can use your own photos, drawing, text.
In reality, it's highly improbable that somebody will duplicate exactly another stamp design.
If it makes you feel better, there are MILLIONS of identical copies of many regular stamps issued by national postal administrations - and that's fine, too.
Take ANY bear stamp from USPS, for example.
They mass-printed it - could be millions.
Many have sold, so there are hundreds of thousands of collectors just like you, who own a bear stamp just like yours.
IDENTICAL.
Don't worry now about petty differences like centering and such.
Take ANY bear stamp that YOU can design, buy and sell.
You can use a photograph, etc., yours or not, and you can customize it as much as you want.
PERSONALIZED.
You can buy a sheet of 20, at minimum. Or at maximum, if you so choose.
Think about it.
Also: how many regular stamps do you have in your collection about the TIBETAN BLUE BEAR (Ursus arctos pruinosus), for example?
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.Was that crickets that I heard?