Can I have two very different public keys?

I have the public key I generated using PGP in 2006: PGP PUBLIC KEY BLOCK-----Version: PGP for Personal Privacy 5.0. It is working without problems.

I’m teaching someone how to use Kleopatra, so I exported my public key going through the steps with her over the phone. The PGP PUBLIC KEY BLOCK-----Version: GnuPG v2.0.20 (MingW32) that was generated is much longer than the old one.

I’m confused. Can they both be valid public keys?

If they both work, and can be managed within Kleopatra, they’re both valid. Perhaps the earlier one is RSA-1024, and the recent one RSA-2048? Have a look at the certificate details, and see how they differ.

If it is the same key, the longer key size may be due to additional information being added to the key, such as signatures.