Battleship Revenue Proprietary 5/8c Overprint Date Is 1999, Error?

Hello all Stamp Masters,

I got this Revenue because I found the Overprint date of 1999 odd for a Stamp from 1898.
My assumption is that this Overprint was originally from 1899, but that the second digit was accidentally set to "9".

Are these kind of errors rare?
Any more information on this?

Thanks!

looks like someone either goofed or ran out of eights. nice find.

Though I am not experienced on the topic to speak to it, thank you for sharing. I appreciate seeing this.

No problem, thanks for the comments.
I just found this quite weird, so I jumped the gun and bought it.
But I know nothing of such errors on revenue stamps, considering this is a company precancel if I'm correct.

Another interesting Revenue I once found and bought was one that was cancelled by Vanderbilt Treasury.
Just loved the idea of it having gone through the offices of Vanderbilt.

It's a nice embossed cancel, but there is no real way to know whether it was a precancel or not. Embossed cancels are a bit less common, but there are quite a number of them. I would not call the original printed cancel an "error", either. It's more of a "mistake". Someone put in the wrong number plug, that's all. Again, it's a nice collectible, a nice item to find, but it does not have any significant financial value.