How can I choose a secret key for decryption?

[Fabian Neumann]

Hi,

I have two key pairs: one personal, one business. I encrypt a file to
both recipients (aka self): "... -r KEY1 -r KEY2 ...".

Problem:
When decrypting the file, gpg always asks for the KEY1 passphrase. How
can I instead choose which key to use for decryption?

Just imagine I forget the passphrase for KEY1 but still have the secret
key around (and do not want to revoke it, because I'm confident to
remember the passphrase later). Can it be that gpg won't let me use KEY2
to decrypt?

Cheers,
Fabian