An aircraft departed ATL after receiving a revised PDC SID which included the NUGGT FOUR. The crew failed to remove the SUMMT FOUR from the FMC and so had a track deviation on departure.

Narrative

After I loaded the flight plan into the FMS with the SUMMIT FOUR RNAV departure approximately 1 hour prior to departure and I requested the PDC 30 minutes prior to departure via ACARS (PDC). Our departure (SID) was changed by ATC from a SUMMT FOUR to a NUGGT4; we should have caught it; but we did not. The change on the routing comes in between the dashes; (EX:-summt4.summt-); but since the first two way points in both departure (SID) departing RUNWAY 26L were identical. The Captain and I overlooked it; we figured out the problem after the ATC told us to call ATC after passing SUMMT waypoint approx at 15000 feet. We did not have any conflict with another aircraft. At that point we re-checked the paper work and figured out the problem. I do believe that [fatigue] from the prior 14 hour duty day followed by an early duty-in; and the same initial waypoint in those SIDS are contributing factors. If the first waypoint in every SID were different it could raise a flag on the take off clearance; since when you are replying back the clearance you are looking at that waypoint on the screen.