The silver axe in slot 7 highlights the silver axe, as it should, but apparently the empty slot in alt-6 also highlights the silver axe. I have no idea why this would happen.
Can you give more details on what you were doing? For example, were you using the mouse, a controller or number keys to select items in both hands? Also, what inputs were used?
I just noticed it when it happened, but this is all I have on it:
I use mouse and keyboard, have no idea when this started occurring and it disappeared after I’d switched out some items.
I have selections set to 1-8 and alt-1-8, both hands separate on mouse scroll.
I hoped you had something similar already that this specific screenshot could help with 
Since I have very little useful info otherwise.
I’ve not been able to reproduce this so far. How often are you seeing this occur?
Couple times now, no idea what the actual frequency is. Sorry 