Backups Clarification

[SoraMan]

I understand armory is a HD wallet so a single backup will always be valid, which is awesome, but I can't find a clarification on what counts exactly as a "wallet". Does it mean a single specific wallet id, so if I create a new wallet with a new id than that would not be covered and I'd need to back that one up as well, or is all wallet ids created from a unique master key pair for each install of armory using a branching tree hierarchy? 

[goatpig]

One wallet <-> one backup.

There is no relation between 2 wallets, even if they were made within the same process. The root keys are just plain PRNG pulls. If you want to derive several wallets from the same root, you'll have to wait for BIP32 wallets.