This is an issue you may see if you are working on more than one cloned operating system at the same time.
You plug in a SD card that you’ve loaded up with a Dexter image, (or any pre-packaged Raspberry Pi image for that matter), using an imaging tool like Etcher, (or dd, or whatever). You then try to plug in a second SD card with another image cloned from the same source.
One of the SD cards - usually the second - refuses to mount because “it has a signature collision with another disk. . .”
The original image that was packaged up, and that you write to your SD media, comes with a pre-defined UUID, (unique identifier) for the disk - AND that “unique” ID is exactly the same for every disk created from that specific image. The reason is that - unlike other disk cloning tools - tools like Etcher and dd do NOT re-assign a new unique ID to each disk.
(NB: I’m going to post a bug/enhancement request on Balena’s site about this.)
This can be fixed relatively easy on Windows using the “diskpart” utility. I am sure that there are similar utilities available for Linux and Mac systems.
Rather than re-invent the wheel for anyone running Windows, I’ll just link to an article I found that (ahem!), “reminded me” how to change the UUID on the offending disk. In fact, all you have to do is pick a number, somewhere in the existing UUID, and change it to something else, then un-mount, unplug, and re-insert the drive.
Piece of cake!