Originally Posted by Outlaw7
Soon as you hit the copy command the original card becomes unusable. And it does not copy.
Not really true. I've done a DD of my card a few times.
The protection is in the card serial
number. You'd need a card in which you could edit the CID to mirror that of the original. Think of it like spoofing a MAC address. CIDs are usually locked though. Hence the secure part of 'secure digital'. You can buy cards that aren't, but you have to specifically look for them, and even then you need special hardware
to write the CID.
Old Samsung Evo cards used to be able to be hacked to change the CID, but these ones went out of production a few years ago.
All in all, it's more effort than it's worth, and if you already have a Navionics card, new ones are half price