Hello @Valaetoshiru !!
This is not a bug. This is intentional so you have the option to add additional buttons per item.
Here are the instructions as posted in the Official Em-8ER Discord for clearing and changing keybinds:
If you have any questions on what some of the keybinds are, be sure to check out the rest of the "Demo-Controls" channel located in "Multiplayer Demo Section" in the Official Em-8ER Discord.