The correct way of doing this is to specify multiple "IdentityFile" lines in your ~/.ssh/config
The id_rsa[.pub] files represent a keypair and isn't supposed to contain multiple identities, but it's easy and perfectly valid to use several keys, either by using -i or IdentityFile. Closing as this is not a bug and not really a missing feature.
The correct way of doing this is to specify multiple "IdentityFile" lines in your ~/.ssh/config
The id_rsa[.pub] files represent a keypair and isn't supposed to contain multiple identities, but it's easy and perfectly valid to use several keys, either by using -i or IdentityFile. Closing as this is not a bug and not really a missing feature.