For multiple GMail accounts with Gnus, you have to make two nnimap
entries in your gnus-secondary-select-methods with distinct
names:
(setq gnus-secondary-select-methods '((nnimap "gmail"
(nnimap-address "imap.gmail.com"))
(nnimap "gmail2"
(nnimap-address "imap.gmail.com"))))
Your netrc entries will then be:
machine gmail login account@gmail.com password "account password" port imap machine gmail2 login account2@gmail.com password "account2 password" port imap