Divinity Original Sin 2 Arx Doctor Basement chests guide?
Solution 1:
Saving and loading after looting one of them (Kvyn's) and experimenting with different effects on the other (Ruaney's) got both to open for me...
Solution 2:
They changed it in the most recent patch so that you can't lockpick them anymore, so I guess that it was a bug that you could before, which is why people said that they could in older posts.
The way to open them now is to cast Blood Rain on them, though it'll only open one of the equipment chests and lock the other, depending on which one you cast it on (50/50 if you cast it on both at the same time, I guess?). I saved and reloaded after opening one that way and that made it so the other one was unlocked and the one I had opened first was locked.
To be honest, I'm not really sure what the intended interaction is for these chests and what's a bug, but what I mentioned seemed to work for me.