Uh, more likely, those cell towers are for different cell providers. You know they don't all share the same towers, right?
Once again, stingrays are portable spying devices. When cops want your data they don't even need one of them, they can just demand it from the cell providers. Stingrays are just handy because they can take it anywhere for real-time results and skip that pesky paperwork that gets all of those darn civil libertarians (aka citizens) all riled up if they discover it.