Can you use one collateral for two different loans?

That is up to the creditors. If the 2nd is willing to accept the c ollateral even if there is already another creditor with a superior lien, that is pretty standard. Think of a first and second mortgage on the same piece of real property.

You can as long as both lenders know about it. If you don't tell the lenders what you are doing... it is called "fraud".

Second mortgages are a typical example of using one collateral for two loans. All loans are subject to the lending practices of the institutions to which application is made. Getting two loans on a single motor vehicle would probably not be possible, unless perhaps the car is worth really big bucks because it is very rare and in excellent shape. In other words, collateralizing personal property for two separate loans is probably not possible, but it is done frequently with real estate.