Phoenix and Deer Valley both use parallel runways. Sometimes to see the airplanes approaching the airport, they may appear to be in conflict. They're not.
Other airports around Phoenix have traffic approaching and departing all the time as well, such as Mesa, Williams Gateway, Chandler, Scottsdale, etc. These outlying fields aren't far from the city either, and can be quite busy at times. Naturally, the trafic from these fields isn't necessarily going in the same direction as the traffic using Phoenix Skyharbor...but it could appear to be a conflict...it's not.