I have an itinerary that has my last leg going XXX-ATL-YYY.

I just realized that I need to end up in a different place.
So, what I want to know is...can I make a reservation that starts in ATL... fly XXX-ATL...then just skip my ATL-YYY segment...and pick up a new itinerary, ATL-ZZZ?

My worry is that the computers will have a problem with this, as my ATL-ZZZ segment would takeoff before my ATL-YYY segment.

Thoughts?