From the man page for netrc, it would appear that ftp will only use the first instance of a machine name in a file ...
Identify a remote machine name. The auto-login process searches the .netrc file for a machine token that matches the remote machine specified on the ftp command line or as an open command argument. Once a match is made, the subsequent .netrc tokens are processed, stopping when the EOF is reached or another machine token is encountered.
Greg.