Yeah, I'm thinking the Greedo scene was shot later with the information added to it when Lucas didn't have time to make the effects for the Jabba scene. There's also an alternate Greedo scene (with a less articulated mask) included in some rough cuts of the Cantina scene.

There's another example of this in some of the other films deleted scenes.

ROTJ

Originally, the sandstorm scene had the dialogue about Han thanking Luke, Leia reminding him about the fleet assembling, and Luke keeping a promise to an old friend.

When the Sandstorm scene kind of looked ugly and they decided to cut it, they made a new scene with most of the dialogue moved to Luke listening to it on his X-wing as they depart Tatooine.


In ROTS there's an alternate scene where Obi-Wan, Mace and Yoda are talking in Yoda's room about Palpatine and removing him from office/arresting him. Most of the dialogue from this scene was instead put in a holographic briefing with Obi-Wan not present and some of Mace's dialogue given to Ki-Adi instead.