Another Heer Einheitsfeldmutze

[MarcoPennisi]

Never too late for revision & addenda.
The odd 8-digit "RB NR." is a major and decisive telltale sign as well, the maker may have missied with purpose the correct 9-digit number sequence.
As JPhilip pointed out, the too-new-to-be-true condition is not a discriminating factor.
MP

[S.Vestae]

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[MarcoPennisi]

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You witty!
But the cap may not be that old.