With image editing software just about anything is possible.
Everyone has noticed how clean the pacifier was. It could have been planted or photo-shopped, but with this photographers record now, anything is possible.
Are there any other photos by OTHER photographer of the baby with the pacifier
There are two other photos by Anwar Amro of AFP. They are posted at Getty Image #71541368 and #71541349. These are taken at the same time as this one so I think it's right to say the soother was not photoshopped in.
The first one must have been taken just as Green Helmet Man raised him up because it shows a lot of sandy stuff falling off the body. If you look very closely at the soother there is some dust around the edge of the big part but that is probably from the falling dust. There is a picture of Green Helmet man kneeling by the baby before this that is posted towards the end of last night's thread. I think that one was by Hajj. You can see just a trace of the soother from the perspective of that photo which was taken before he was displayed to the world as in this one.