This is possible if your advisor agrees that the work you did for CSE599 would be equivalent to CSE523 (CSE523 and CSE524). If s/he does agree, discuss with the Graduate Director. If s/he does not agree, then you have to redo CSE523 and CSE524. Note also that such conversation, when approved, only means that one course is acceptable in lieu of another for the purpose of counting graduation credits. This will not change your official transcript.