I am not sure it is a reused item. I mean I would be very surprised because the whole series were shot in Hungary and we only had one non Hungarian in the props department and it was DERYCK BLAKE as the prop master. The rest of the props guys were all Hungarians and none of them has any connections credit wise to any Mandaloran episodes.
The only thing I can imagine if they had a reshoot of that scene and they did it in England instead coming back to Hungary. Which would be weird considering we had everything packed and stored in warehouses in Hungary but I’ve seen many weird things in this business so everything is possible
also I have no idea which scene is this and how much they used this gun at all. If it is something major and they visibly use it in many scenes and cuts then it is much more likely a prop they used here in Hungary.