CleanUp.exe

This is going to be boring for those of my loyal readers who don't happen to be software developers. Sorry.

while( inputFiles.Items.Count > 0 ) {
  string file1 = inputFiles.Items[ 0 ].Text;
  string extension = Path.GetExtension( file1 );
  inputFiles.Items[ 0 ].Remove();
  using( BinaryReader brA = new BinaryReader( new FileStream( file1, FileMode.Open, FileAccess.Read, FileShare.Read ) ) ) {
    foreach( ListViewItem item2 in inputFiles.Items ) {
      bool identical = true;
      string file2 = item2.Text;
      if( !file2.EndsWith( extension ) )
        continue;
      using( BinaryReader brB = new BinaryReader( new FileStream( file2, FileMode.Open, FileAccess.Read, FileShare.Read ) ) ) {
        if( brA.BaseStream.Length != brB.BaseStream.Length )
          continue;
        brA.BaseStream.Seek( 0, 0 );
        for( int i = 0; i < brA.BaseStream.Length; i++ )
          if( brA.ReadByte() != brB.ReadByte() ) {
            identical = false;
            break;
          }
      }
      if( identical ) {
        ListViewItem result = new ListViewItem( file1 );
        result.SubItems.Add( file2 );
        lstResult.Items.Add( result );
        break;
      }
    }
  }
  progressBar.Value++;
}

Cool, eh?