"Obviously, they're playing for their lives," Panthers coach Peter Horachek said. "Getting that second one and tying it up was a great momentum boost for us."
Dallas took the lead 45 seconds into the game when Benn poked the puck past a defender and then wristed a shot past Luongo for his 33rd goal.
Benn, who scored 40 seconds into Saturday night's 5-2 win at Tampa Bay, has three goals in two games.
Dallas made it 2-0 just 39 seconds into the middle period when Seguin scored his 36th of the season during a power play.
Seguin's shot from the left circle went off the stick of a Florida defender and into the net, giving Seguin his fourth goal in four games.
The Stars also struggled against Tampa Bay on Saturday, when they nearly blew a three-goal lead before pulling away in the third.
"Tough points to lose, it wasn't a good game for us," Seguin said. "No excuses even though it was back to back. We expect better."
NOTES: Pirri has a four-game point streak and has 12 points in 15 games. ... Benn has 21 points in 19 games. ... Dallas G Tim Thomas, traded by Florida to the Stars on March 5, didn't play. Thomas has been in just two of the past 10 games. ... Dallas forward Ray Whitney missed his second consecutive game because of a lower-body injury.