Yes, it would have to do with the 1.0 service that's registered to the account. As long as you're not paying for the first service (the 1.0 service) you're only paying one sub fee. IF you did want to use both, you can, you'd just have to pay for both subs.
Current: FFXIV | EVE Online (again)
Former: FFXI | The Matrix Online (FOREVER!!!) | STO | SW:TOR | EQ2 | WoW | Florensia | RF Online
FFXI :: Valefor :: Dareknight, Darexius
FFXIV :: Valefor :: Dare Knight
EVE Online :: Dare Knight, Hazel Knight, Rex Knight