Originally Posted by
Fiosha_Maureiba
syntaxlies and Zenaku are correct. If you "discover" a way to run two or more instances of the FFXIV client on a single machine, you do so at your own risk.
If you were using two computers, two keyboards/mice/gamepads, that would be a different story.
On the manual multi-boxing note, FFXIV has been very difficult to multi-box versus say Aion. Managing the distance of a mage to be able to provide cures, avoid area AoEs and spawned mobs, follow without snagging on corners or losing the target by invisible zones, or in anyway contribute offensively to combat has been difficult. To me, it's not fun, not efficient, and hasn't been worth it.
I imagine you want to take advantage of that buddy pass though to transfer items between characters, have some extra inventory space, and maybe conserve some anima. But if you discover a way to do this on a single computer, you do so at your own risk.