Siscia Fallen Horseman with symbol 4 in mint mark

[agord]

I received this today and wanted to share it. These symbols were used during Constans lifetime on some of the Phoenix and Galley types but are not recorded after his death. I think this mark is supposed to be a retrograde Z, making this Ric VIII Siscia 352/361, but the Z seems to have been re-engraved with the symbol 4 mark.
For more info on these symbols see https://www.forumancientcoins.com/board/index.php?topic=93305.25

[agord]

 I would like to clarify that I think that it was the die that was re-engraved, not the coin tooled. The only way to prove that would be by finding a die match coin.

[Victor C]

I have had quite a few re-engraved examples.

The B in the reverse field at first looks retrograde; but looking closer it seems engraved over... like S over EI in an attempt to change it to BI.

In the reverse legend of the second coin, it looks like the engraver made an error and then re-engraved it-- the first S of CAESARIS has something under it.