old_contents: import bpy
  
  def find_seqs(scene, select_marker):
      sequences = {}
      sequence_flags = {}
  
      for marker in scene.timeline_markers:
          if ":" not in marker.name or (select_marker and not marker.select):
              continue
  
          name, what = marker.name.rsplit(":", 1)
  
          if name not in sequences:
              sequences[name] = {}
  
          if what in sequences[name]:
              print("Warning: Got duplicate '{}' marker for sequence '{}' at frame {} (first was at frame {}), ignoring".format(what, name, marker.frame, sequences[name][what].frame))
              continue
  
          sequences[name][what] = marker
  
      if "Sequences" in bpy.data.texts:
          for line in bpy.data.texts["Sequences"].as_string().split("\n"):
              line = line.strip()
  
              if not line:
                  continue
  
              if ":" not in line:
                  print("Invalid line in 'Sequences':", line)
                  continue
  
              name, flags = line.split(":", 1)
  
              if flags.lstrip():
                  flags = tuple(map(lambda f: f.strip(), flags.split(",")))
              else:
                  flags = ()
  
              sequence_flags[name] = flags
      
      return sequences, sequence_flags
new_contents: import bpy
  
  def find_seqs(scene, select_marker):
      sequences = {}
      sequence_flags = {}
  
      for marker in scene.timeline_markers:
          if ":" not in marker.name or (select_marker and not marker.select):
              continue
  
          name, what = marker.name.rsplit(":", 1)
          what = what.lower()
  
          if name not in sequences:
              sequences[name] = {}
  
          if what in sequences[name]:
              print("Warning: Got duplicate '{}' marker for sequence '{}' at frame {} (first was at frame {}), ignoring".format(what, name, marker.frame, sequences[name][what].frame))
              continue
  
          sequences[name][what] = marker
  
      if "Sequences" in bpy.data.texts:
          for line in bpy.data.texts["Sequences"].as_string().split("\n"):
              line = line.strip()
  
              if not line:
                  continue
  
              if ":" not in line:
                  print("Invalid line in 'Sequences':", line)
                  continue
  
              name, flags = line.split(":", 1)
  
              if flags.lstrip():
                  flags = tuple(map(lambda f: f.strip(), flags.split(",")))
              else:
                  flags = ()
  
              sequence_flags[name] = flags
      
      return sequences, sequence_flags
subject: Make sequence marker types (:type) case insensitive