Two keys in ~/.ssh directory

I originally had a DSA public key in my ~/.ssh directory on my server id_dsa.pub. The corresponding private key id_dsa is stored on my local machine.

I then generated an RSA key pair directly inside the ~/.ssh directory on my server which now contains id_dsa.pub, id_rsa.pub and id_rsa.

Shortly after, I found myself unable to execute any bash commands. Commands such as ls and pwd were returning command not found.

I then terminated the ssh session and tried to reconnect. However, now I am getting Permission denied (publickey). What happens when you have both rsa and dsa keys in ~/.ssh directory, do either keys work or does the rsa key supercede the dsa key?