I dont think so. If lefty were told to whack Donnie, then the order would most likely have came from Sonny Black. And later after being told that Donnie was an agent, they talk about Donnie, and says "No was Donnie is a rat.. If I didnt know Donnie".

One thing I dont understand is why one from the crew is escorting Donnie with a gun to his neck from the car two times. First when they give Lefty the tiger in the beginning and way later when they have just whacked the Sonny Red crew.