Problems with two active encryption subkeys

[Sven Klomp]

Hi,

since I bought a Crypto Stick [1], I had to add an additional RSA subkey for encryption, since the stick doesn't support Elgamal. Thus, I have two encryption keys in my public keyring now. How does gpg decide which one to use for encryption? I thought, that every key is used and I can decide to use the Elgamal or RSA key for decryption. But it seems, that only one subkey is used (RSA) for encryption.
Do I have a general misunderstanding of the concept?

Sven

[1] http://www.privacyfoundation.de/crypto_stick/crypto_stick_english/