In episode The Tok'ra II. Sam, Her Father and the ...Lover Boy was leaving the Tok'ra under attack planet. They are now in front of the Gate, then the Stargate lit up (as if being dialed as destination). Sam says, they are dialing here.. and also said, not if we dial Earth first.
She dialed earth but unsure who dialed first, if their current gate is a destination or the entry point. Her father stated that they dont have a choice. Lucky day.. they arrived to Earth!
Question is: How can a destination gate lit up as if being dialled from another source, when the address is still incomplete.