It's been explained to you that the keepers of the register (now long dead) decided (for reasons best known to them, which are lost to history) to withdraw and re-issue certificate numbers in the early days of the register.
There doesn't appear to be any sense to it looking back, but that's the situation: there's nothing the current registrar can do about that, and there's little to be gained by throwing terms like 'Hitler' about.
Now machines keep the register number in perpetuity: like it or not, the original register number for your machine is now assigned to another one.
If the provenance of your machine means that it's identifiably veteran, you'll be able to have it included on the register again, under a new number.