Are prefabs guaranteed to be loaded only once during the runtime of a game?

I've just started using unity so am trying to find the best way of structuring things in the editor.

My question is, are prefabs guaranteed to be loaded only once during the runtime of a game? More specifically if you have two references to the same prefab linked to script variables in two separate game objects would you be able to rely on them being reference comparable? Of course you could always manually assign an id of some kind but that seems rather clunky.

If what I'm asking isn't clear, here is an example use case:

Say you had a set of inventory item types, each one was a prefab with the name and specs of the item. In the editor you could have a shop object that has an array of sellable items. It would be nice if you could just drag the items available from the project pane into the shop script in inspector. If you then had say an pickup-able item in a scene that also referenced this prefab would it be safe to just compare the prefab by reference to see if you could sell your item in the shop or would you have to match by name/Id? I'm trying to make it all data driven and avoid enumerating all items in code. Maybe there is a better way of doing this sort of thing which I'm not aware of.

Thank you