The tricky part about names is the fact that many colonies get split before making it to vendors (or get collected again at a later date or extremely similar piece in another location from another diver even), so 2 (or more) vendors get the same piece and name it something different eventho they look exactly the same and may even be from the same original colony they are not the same in some peoples eye.... especially those that want lineage, because they want the actual piece from the original namer and not a potential knockoff piece.
That said, if they got the original named piece knowing it was that piece through the line, and called it something different then yeah thats bad business but IMO if they got it in a fresh shipment said hey this looks like this.... but it didn't come from whoever named it so it isn't truly that piece lets call it this and set the price at this there is nothing wrong with that IMO, and if someone wants to pay $30 more for a very similar piece to a cheaper one that is their choice