For this to work, you must have the "all materia master" gameshark code on(the one that give you master summon, master command and master magic materia)...
In the shinra building when fighting rufus for the first time, when it asks you if you want to change tifa and clouds materia, say yes.
Cloud keeps his materia, because the cheat keeps them there at all times, but the appear doubled in you materia inventory!!!
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