Assuming an implementation in which player monsters can steal the Amulet of Yendor from you: they may instead steal an imitation amulet you are carrying in main inventory.

Up for debate whether they should have, say, a fixed 50% chance of stealing the real Amulet regardless of how many fakes you are carrying, or whether they should pick one of your apparent Amulets at random, which would give an advantage to carting around more fakes.