Multiple public PGP keys for the same private key?

My scenario is the following:

• my wife and I want to encrypt/decrypt files
• we want to be able to decrypt each others' files
• we don't want anyone else to be able to decrypt our files

Is there a way to do this?

For instance, if we would both use the same private key to decrypt the files then could we use two different public keys to encrypt the same files?

I assume there is a possibility for this because I was looking at the source code of openpgp and could see that the method for encrypting accepts an array of public keys. It's just that I don't know how to generate multiple public keys for the same private key.

For the record, I'm using Windows and Kleopatra to generate the keys, but I can also use gpg on linux if necessary.

Encrypt the file with my public key and my wife's public key. Then later, I can decrypt the file with my private key and she can decrypt the file with hers.