Two kinds of Bitcoin addresses issued with bitaddress.org

I forked the bitaddress.org repository and generated a new paper wallet. On the output page there are two addresses generated: one "regular" and one "short address". Both start with 1 and are legacy addresses. I transfered a small amount to the short address and checked the balance on blockchain.com. The problem is that there is only a transaction on the short address. I expected the addresses to be linked somehow. What am I missing here?