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Inventory overflow glitches allow one to carry 5 (or more, depending on the method) wands, select them via [Previous] and [Next] item key-bindings, and fire them. They also enable overloading the Spell Capacity on a wand.
Carry more wands! - Pand1024 --- demonstrates both a smuggling and alternative window-switching overflow technique which allows for 5 or more wands; note that running in windowed mode may be an additional prerequisite, at least on some window managers
See video guides by Aliasbot, for wands, and for spells: