Magically Ambidextrous
Skulduggery, a user of two types of Magic is thus Magically Ambidextrous.
Magically Ambidextrous
Magic Type Magically Ambidextrous
Power The Power to use two or more forms of Magic or rather, to be Magically Ambidextrous.
Notable User(s) Skulduggery Pleasant

Magic comes in a variety of types, though they are usually classed as Elemental, or an Adept Discipline and usually sorcerers can only use one form of magic but people whom are magically ambidextrous can use two - or possibly more disciplines of magic. Note that mages whom haven't gone through The Surge and can use more than one form of magic are NOT magically ambidextrous, also note that those who know their True Name aren't magically ambidextrous as the True Name is the source of one's Magic.

Known combinations of magic.

Skulduggery Pleasant - a user of both Elemental magic and Necromancy