medieval goldsmiths

In medieval times, goldsmiths would often offer to store gold in return for a fee. They provided anyone depositing gold with a warehouse receipt, which represented a legal claim on the goldsmith to exchange the receipt for the amount of gold written on it.
a. How are the medieval goldsmiths like modern banks, and how are they unlike modern banks?
b. Is multiple deposit creation possible in this system? Does your answer depend on whether the warehouse receipts can be bought and sold and redeemed by someone other than the person who deposited the gold?