Issue with upgrade finder


So this is a minor issue I have, but I was looking at upgrades for my rogue, I recently am trying assassination, and I got a Lungbreaker dagger to drop. I was just plotting upgrades and I wanted to see how say a second Lungbreaker would compare to say Bloodsipper heroic. I selected offhand in the add to my bag, since I have the first Lungbreaker mainhand. I do not believe it matters if you select offhand or mainhand for a rogue though. But my issue is it just says Owned for the Lungbreaker. Even when I just search upgrades from ICC 25 it wont show me if a 2nd Lungbreaker would be an upgrade, it just shows it in my bag. I believe this issue only really matters for classes that might dual wield the same weapon like fury warriors and rogues.