Dating Conduct Medals from the 1800s by Allen and Moore, Birmingham

I have a question about medals made by Allen and Moore, Birmingham, UK (1844-1855), very well-documented here on the Numista site: https://en.numista.com/catalogue/mint.php?id=4329

My family has one of their Good Conduct medals, exactly like the one listed here: https://en.numista.com/catalogue/exonumia238248.html

My question is about the dates in the listing: "Late 19th / Early 20th." This appears to be inconsistent with the company going out of business in 1855.

That said, we think the medal that we have belonged to my great grandfather who left school around 1876. I am hoping someone has some insight into this.

One explanation could be that someone acquired a batch of these medals in 1855 and kept selling them?

Any insights much appreciated.

Stephen in Coventry

Then the last minted medal would still have been 1855 making that the end date.

probably the information added on Numista was copied from a listing which just stated incorrectly Late 19th / Early 20th