Yeah, multiple ways, it's not tied to Mac address
U can use official methods built into the system menu to transfer mii's and most gamesaves, for those that aren't supported u can enabled the priiloader hack to enable this, or use savegame manager gx (or use it for all regardless). U can backup channels in wad form using bluedump mod. Heck u could even clone a nand.bin from one wii for a different wii by opening it with modmii (or manually using punetwiin), but this is extreme and not really recommended.
U could also use showmiiwads's showmiinand view and back things up that way
I wouldn't be surprised if I forgot yet another method... u could just dump your nand directly to emunand using gx or another tool and just launch backups right off the emunand device using a usb loader or neek