Is this legal or not?

My mouse has the same buttons; most mouse software now comes with the ability to do multiple button presses with one click.

No, this is not within the scope of the rules and can certainly earn you some kind of account action. The law of the land is “one button click, one action.”

I get why mouse manufacturers make these features available; they’d be very useful in some situations. But they are a no-no for WoW.