You buy a share. You now rent it to someone else. They sell the share again (and hope to buy it back later at a lower price). Same share has been sold twice. Th

You buy a share. You now rent it to someone else. They sell the share again (and hope to buy it back later at a lower price). Same share has been sold twice. The 2nd buyer of that share can then rent it again to another seller which increases total short interest.