When you have a chain of borrowers you can. Party A lend to Party B then Party B lends to Party C. ect.
I made it sort of simple but it happens because of proxy share generated by the machines to place orders. So the number of contracts that are out at points can exceed the number of real shares but eventually it will all correct back to the original outstanding as the contracts are full filled. There never is any additions stocks but there is more owed out in this circumstance.