Disclosed are various embodiments of multi-layer identifier labels. In one embodiment, a multi-layer identifier label includes an upper layer bearing a public identifier, a lower layer bearing a private identifier, and an adhesive backing below the lower layer. The upper layer may be removably attached to the lower layer, and the lower layer may be non-visible underneath the upper layer. Peeling away the upper layer to reveal the lower layer may be a tamper-evident action.