As I have a sealed spare mini..., I have a copy of each on laptop & on the USB stick I use for the mini - (moved to a folder once installed on stick). That automatically creates a handy backup for me any way.
**OFF TOPIC** I do wonder how the ZX Spectrum Vega went in this regard, did it even get any updates? The official site looks like it's been taken over by hackers, or rather it's a mess of someone taking the piss out of the Vega+ project any way. Not checked any forms though.