The sf*Database classes are limited to one resource when multiple databases are specified in databases.yml and the host, username, and password are all the same.
I propose specifying the respective argument as true by default, because the sfDatabaseManager already ensures that the respective connect() is called only once.
* sfMySQLDatabase, the class does not specify the new_link argument in the mysql_connect function.
* sfPostgreDatabse, the class does not specify the PGSQL_CONNECT_FORCE_NEW option.
* sfPDODatabase, sorry, but I'm not sure how this one works.
For more information as to how I came upon this specific problem, I have posted on the forum here, Multiple databases, problem and solution.
cheers,
Alex