Suppose you have in your inventory:
k) a scroll of enchant weapon to-dam
l) a scroll of satisfy hunger
Reading the enchant scroll asks you to select a weapon, and your inventory turns to:
k) no more scrolls of enchant weapon to-dam
l) a scroll of satisfy hunger
If you select a weapon (for me it was a +7 rapier wielded as an offhand weapon) and the enchantment fails, both scrolls are used up (you don't even get fed by the satisfy hunger scroll in that case).