Someone mentioned this in a January post but the title had a "suggestion" instead of Bug. I'm pretty sure this is a bug and not intended.
If you kill an enemy champion they drop their weapon in the loot, but they dont actually lose it. They keep it and since champions don't die they come around and give you the weapon again. This could be a serious exploit and warrants a fix imo.
After all who needs to set up an economy when you can farm yummy Toxic daggers that are worth 1200g .