So, I still have a dupliacte of the Broken Grip of Legends from a previous version, despite already having Excalibro.

Should I just treat it as a memory of an older version? Because if I am honest, having that duplicate annoys me a bit, because it clutters up my weapons menu...

It not possible to get a second grip of legends anymore, but it still remains in your inventory in save files where that problem appeared before the fix. There is no option in the current version, which would allow you to get rid of the grip.