Just make sure you format it to FAT32 first, cards larger than 32 GB are ExFAT formatted by default. Windows' built in formatter won't format 64 GB or larger cards to FAT32, so you'll need a 3rd party tool like guiformat.
See if your console boots without an sd card. If it does boot you're likely using menuhax or you installed a9lh recently. if it doesn't boot (light turns on then off) then just do https://3ds.guide/updating-a9lh
Likely, if you just clone your SD then on one uninstall all games, you should be able to install other games. But I would rather get a bigger SD card than a second one and hassling with swapping around.
also on a related note, i should start treating my keyboard better, my friend saw my keyboard while visiting my house and he said "holy shit why is it this dirty do you like shove it up your ass right after you clean it or something"