code: def do_keyframes_overlap(self):
          
          skl = self.sorted_key_list()
          for i in range(len(skl)-1):
              this_time = self.dct[skl[i]]['__abs_time__']
              next_time = self.dct[skl[i+1]]['__abs_time__']
              if abs(next_time-this_time) < 1e-6:
                  # key frame times overlap
                  return skl[i]
          # Return None if all passed
          return None
docs: Checks for keyframs timing overlap.
  
          Returns the name of the first keyframs that overlapped.