so basically this is only a co-op bug when you and your friend spam click the furnace and while the furnace is smelting any bar you can duplicate it so you can get 2 bars instead of 1 which is neat but its a bug none the less.
Hi! In an effort to keep similar reports together, I've locked this thread as a duplicate of https://forums.stardewvalley.net/threads/3970/. If you have additional info about this issue, please add it to that thread!
The main thread for an issue is picked based on multiple factors, we won't always pick the earliest thread that reported the issue.