Minecraft v1.16.5
Forge v36.1.16
Locks v3.0

Chests spawn with two locks on them, and dropped two when unlocked.

it happend to me on the locks-1.16.5-3.0.3.jar version on singleplayer

Very strange, I thought I fixed that before releasing..? Is this happening on a server or client world? If the former, then can you check if it happens in a singleplayer world? Also try relogging into the world. Is there still 2 locks?

It was on a server. I can try a singleplayer world tomorrow.

Tried it on a singleplayer world with just the Locks mod and there was only one lock generating on chests, so probably related to servers.

Strange, I haven't been able to reproduce this on my own server. Are there any specific circumstances when this happens? Or does it happen to all chests for you?

Hmm, I'm not sure. I'll have to check again. It's a pretty big modpack, so something could be interfering. Maybe Quark? It replaces chests during world gen with its own chests.

Seems to be all chests that spawn with a lock on the server.