98 Trident Fuel Lines... T ?

Hello everyone. I have a newly acquired 1998 trident 900. The tank was disconnected and I was told the petcock was bad. The petcock only has one in from the tank, and one out to the carb, however there appears to be two fuel lines as well as one vacuum line. There is no t connector anywhere to be found.
When I attach my auxiliary tank to one of the fuel lines to start the bike, fuel flows out of the other unattached line. The guy I bought the bike from told me he rode this bike for 5 years and that it sat for the last three, and that it had a bad petcock. Can I plug one of these lines? Or is a t connector necessary? All the best

 

Never mind. I figured it out. The original petcock has two out ports

 

However I would like to use an aftermarket petcock that only has one out port. Is this possible?