RuneScape Classic Wiki
RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Bedobin Copy Key
The Old School RuneScape Wiki also has an article on Bedobin Copy Key.

The Bedobin Copy Key is a key used during the Tourist Trap quest to open a chest in Captain Siad's room. Players must first distract him before they open the chest. It can be obtained from the Bedabin Camp west of the Desert Mining Camp.

Players who open the chest get the following message:

"I wonder what is inside...
While the Captain's distracted, you quickly unlock the chest.
You use the Bedobin Copy Key to open the chest.
You open the chest and take out the plans."