Thornbury Hoard

We went to Bristol City Museum & Art Gallery on Sunday. Among other exhibits, they had the Thornbury Hoard - 14,600 (I think) small coins, each one a nummus of copper alloy, from around 330 AD. They had been buried in an urn or pot.

There was a bit of commentary with them - when they were made, where they were made, who was depicted on them, how they were found etc. But it didn't address the question of why there were so many coins of identical value.

So, oh wise FList - any ideas???