If you want to transfer from modded to normal and viceversa no need for an extra copy
If you want to play on both switched and the same Time, you need another copy
Wonka said "enjoy it" XD
Jokes aside, I said use at your own risk, page also said the same.
I updated my switch by mistake because I didn't updated legends ZA, when I tried going online on sysnand, the prompt for update appeared and didn't let me...
No te apures, no hay problemas en usar save de otra persona, yo personalmente prefiero solo compartir el archivo del mapa, solo es cambiar el acres.nhl y listo.
Pero puedes usar la partida de otra persona y cambiarle nombres sin problemas