Widebody; Low Wing; 3 Turbojet Eng
Air Traffic Control Fully Certified
Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance
Human Factors; Procedure
Aircraft X; and Aircraft Y; departed MEM simultaneously. Aircraft X departed Runway 36L. Aircraft Y departed Runway 36C. I noticed Aircraft Y commencing a left turn into Aircraft X at roughly the same altitude. I immediately turned Aircraft X left heading 230 and amended his altitude to maintain 3;000 FT. Once standard IFR separation was established; I sent Aircraft X on his way and climbed him. There are two north SIDs that are closely named (CRSON and CASLN). One of the two needs to be renamed. Aircraft Y was supposed to have been on the CRSON1 departure as cleared. In fact; the aircraft was navigating via the CASLN1 departure. That was the root cause of the issue; I believe. This is not the first occurrence that I know of. The last time; there was not an aircraft on departure from another runway.
M03 Controller described a developing conflict when traffic issued the CRSON SID was navigating via the CASLN SID; the reporter noting that this was not the first instance of pilots confusing these similar SID names.