OptionConflictError: option -l/--limit: conflicting option string(s): -l

File "youdl.py", line 176, in <module>
    main()
  File "youdl.py", line 160, in main
    parseOptions()
  File "youdl.py", line 39, in parseOptions
    help="max number of videos to download", metavar="Integer")
  File "/usr/lib/python2.7/optparse.py", line 1020, in add_option
    self._check_conflict(option)
  File "/usr/lib/python2.7/optparse.py", line 995, in _check_conflict
    option)
optparse.OptionConflictError: option -l/--limit: conflicting option string(s): -l