Can my apartment make me move my staellite dish but not force other residents to to the same?

ok, in my apartmet I have a regular dish network satellite dish that was installed by Dish network. The dish is on a tripod in my balcony, not screwed to anything, but the arm of the dish hangs over the railing about a foot. I just received a letter stating that the complete dish and any part of it must be within the balcony and that I needed to have written permission and a separate deposit before installing a dish even if it was inside my balcony. I agree with them on the first part, but when I asked why does another resident have a 20ft pole sticking out his balcony with the dish looking over on top of the building, I was told he was granted permission to do this because his installers asked if they could install the dish this way. Can they do this? Can they allow other residents to have things extending out their balconies but not everybody?