Morgan, recently suspended and criticized by his own manager for questionable acts on the field, left Florida catcher Brett Hayes with a separated shoulder Tuesday night after a home plate collision in the 10th inning.
Florida's Chris Volstad hit Morgan with a pitch in the fourth inning this time. The speedy leadoff man then stole two bases with his Nationals trailing 14-3.
Volstad threw his first pitch of the sixth behind Morgan, setting off a wild scene. Morgan took a big swing that appeared to graze Volstad's face - Marlins first baseman Gaby Sanchez clothes-lined Morgan, knocking off his batting helmet and sending him to the ground.
The teams piled up, and managers Jim Riggleman of the Nationals and Edwin Rodriguez of the Marlins jawed at each other.
Morgan, Volstad, Rodriguez and Marlins pitcher Jose Veras were ejected. Morgan was loudly booed when he raised his arms as he was escorted off the field.
Morgan is currently appealing a seven-game suspension for throwing a ball at a fan in the stands in Philadelphia on Aug. 21.
Last Saturday night, Morgan collided with St. Louis catcher Bryan Anderson, who had stepped a foot or two in front of the plate. Riggleman later called Morgan's actions "unprofessional."
Washington reliever Doug Slaten and Riggleman were ejected after Sanchez was hit with a pitch with two outs in the seventh. Four batters were hit overall.
Wes Helms had three hits and five RBIs in the Marlins' highest-scoring game of the season. Mike Stanton, Brad Davis and Cameron Maybin homered for Florida.
Logan Morrison and Hanley Ramirez each scored three times through the first three innings as the Marlins took a 14-3 lead. Florida scored five runs in the first, five more in the second and four times in the third.
Volstad (9-9) wound up with the win.
Scott Olsen (3-8) lasted just 1 2-3 innings while losing his sixth straight start. He allowed nine runs and eight hits. Craig Stammen relieved Olsen and was greeted by Stanton's 15th home run.
Morgan scored on Ian Desmond's short sacrifice fly in the fourth. Second baseman Donnie Murphy fell to the ground after catching the ball in short right-center and left the game with a dislocated right wrist.
Davis led off the Florida fourth with his first career home run.
NOTES: Washington 3B Ryan Zimmerman (right hip) was not in the lineup. "He's a little tender," said Riggleman, who added Thursday's off-day will give Zimmerman a two-day rest. ... Morgan stole two bases to increase his season total to 33. ... Marlins 2B Dan Uggla (right groin strain) was not in the lineup for the third straight game.