Probably been mentioned before but my search skills aren’t up to it.
YAY A legendary drop
Oh wait I already have that spell at legendary.
Gear I can change the colour of. Minions can (although rarely) be useful as a duplicate… but a spell. Nothing to do but salvage it.
Given how rare legendary drops are it might be nice to implement a check in the background if the legendary item is a duplicate and if it is swap it for another legendary item. I doubt this will happen because of the amount already on your plates but it would be nice.