Personally, I would refrain from using something like keyclone/ahk/hkn to press two buttons at once, as that is clearly afoul of the ToS. Note: ALT is not a separate key in the context of "single keypress = single action" in the WoW ToS. Strictly speaking, it is a modifier key. ALT, SHIFT and CTRL all fit this, which is further confirmed by the "modifier=xxx" structures in macros. So, pressing ALT+F1 (one key + one modifier) is fine. Pressing F1+F2 (two independent keys) is NOT fine. And yes, Blizzard can tell the difference.

Alternatively, you can create a "/click" macro to press your two hotbuttons "sequentially" but via one keypress, which is what many folks here do for certain things like FTL setups. Don't confuse the mechanic afforded by a "/click" macro with actually pressing two physical buttons at the same time with one keypress. They're most definitely not the same thing.