Dual-wielding.

While this normally refers to weapons, with the right context it should be understood. Dual-weilding is often used for humorous affect in action comedy movies so the connotation should carry over.

"Captain Linux over there is so serious he's dual-wielding keyboards and coding on 3 monitors."

You might call it dual wielding.

Dual wielding is using two weapons, one in each hand, during combat. - wikipedia

While this normally refers to weapons, with the right context it should be understood. Dual wielding is often used for humorous affect in action comedy movies so the connotation should carry over.

"Captain Linux over there is so serious he's dual-wielding keyboards and coding on 3 monitors."