title: Getting this error: argparse.ArgumentError: argument -d/--to-date: conflicting option string: -d
body: <p>I am writing a Django management command. I would like to include optional arguments.</p>
  
  <p>Within the Command class, I wrote:</p>
  
  <pre><code>def add_arguments(self, parser):
      parser.add_argument('-d', '--from-date', type=str, help='Some help text')
      parser.add_argument('-d', '--to-date', type=str, help='Some help text')
      parser.add_argument('-d', '--from-type', type=str, help='Some help text')
      parser.add_argument('-d', '--until-type', type=str, help='Some help text')
  </code></pre>
  
  <p>But whether I run the command with or without arguments, I get the following error:</p>
  
  <pre><code>argparse.ArgumentError: argument -d/--to-date: conflicting option string: -d
  </code></pre>
  
  <p>What am I doing wrong? Thank you.</p>