Narrative:

Aircraft Y called for departure and VFR squawk code to ZZZ at runway 26L full length. I issued him the squawk; issued a cautionary wake turbulence call for a [larger aircraft] that had just departed and cleared him for takeoff. After doing so; aircraft X called ready for departure at runway 26R for a departure towards 'prado.' I observed aircraft Y not moving and prompted him to begin his departure roll as I had previously cleared a PA28 to land on runway 26L and the aircraft was turning a left base to a mile final. I told the cherokee about aircraft Y departing and to square his base to final turn for spacing purposes. I then went back to aircraft X; and cleared him for takeoff stating that I would call his left turn on course. Throughout the next couple of minutes while the aircraft were departing; I was dealing with other clearances and traffic calls developing to the southeast for [a] jet inbound. I had expected aircraft Y to turn left on course to ZZZ and then turn aircraft X left on course behind aircraft Y. Unknowingly to me aircraft Y had made a slight turn to the wnw conflicting with aircraft X departing the parallel; north runway. Aircraft Y; was not on his discrete beacon code I assigned him prior to takeoff and therefore no conflict alert sounded. Aircraft X alerted me that there was a near midair collision approximately 30 seconds ago. I ensured controller in charge (controller in charge) heard what had happened. I observed aircraft Y had overtaken aircraft X on his wnw heading. I initially wanted to get aircraft X away from aircraft Y so I issued a right 270 degree turn southbound. The controller in charge told me to issue a left turn. I reluctantly amended my clearance and issued the left turn. I wanted to turn aircraft X away from aircraft Y's expected southwest flight path. Instead I complied with controller in charge instructions and issued the left turn. I re-issued squawk code to aircraft Y and instructed him to contact sct. I queried aircraft X about his prado request. We have a VFR reporting point to the south called prado dam; which I assumed he was requesting. Aircraft X really wanted to go to the prado IFR navigation fix. Throughout all of this; numerous other operations were occurring creating blocked radio calls; adding to complexity.change the name of IFR waypoint 'prado;' to avoid confusion with VFR reporting point.

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Original NASA ASRS Text

Title: CNO Tower Controller reported an NMAC when the Controller was expecting the first departure to turn southwest; but it actually turned WNW towards another departing aircraft.

Narrative: Aircraft Y called for departure and VFR squawk code to ZZZ at Runway 26L full length. I issued him the squawk; issued a cautionary wake turbulence call for a [larger aircraft] that had just departed and cleared him for takeoff. After doing so; Aircraft X called ready for departure at Runway 26R for a departure towards 'PRADO.' I observed Aircraft Y not moving and prompted him to begin his departure roll as I had previously cleared a PA28 to land on Runway 26L and the aircraft was turning a left base to a mile final. I told the Cherokee about Aircraft Y departing and to square his base to final turn for spacing purposes. I then went back to Aircraft X; and cleared him for takeoff stating that I would call his left turn on course. Throughout the next couple of minutes while the aircraft were departing; I was dealing with other clearances and traffic calls developing to the southeast for [a] jet inbound. I had expected Aircraft Y to turn left on course to ZZZ and then turn Aircraft X left on course behind Aircraft Y. Unknowingly to me Aircraft Y had made a slight turn to the WNW conflicting with Aircraft X departing the parallel; north runway. Aircraft Y; was not on his discrete beacon code I assigned him prior to takeoff and therefore no conflict alert sounded. Aircraft X alerted me that there was a NMAC approximately 30 seconds ago. I ensured Controller in Charge (CIC) heard what had happened. I observed Aircraft Y had overtaken Aircraft X on his WNW heading. I initially wanted to get Aircraft X away from Aircraft Y so I issued a right 270 degree turn southbound. The CIC told me to issue a left turn. I reluctantly amended my clearance and issued the left turn. I wanted to turn Aircraft X away from Aircraft Y's expected SW flight path. Instead I complied with CIC instructions and issued the left turn. I re-issued squawk code to Aircraft Y and instructed him to contact SCT. I queried Aircraft X about his Prado request. We have a VFR reporting point to the south called Prado Dam; which I assumed he was requesting. Aircraft X really wanted to go to the PRADO IFR navigation fix. Throughout all of this; numerous other operations were occurring creating blocked radio calls; adding to complexity.Change the name of IFR waypoint 'PRADO;' to avoid confusion with VFR reporting point.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.