Create 2 mp3-files during upload?

I have the following code:

function convert_audio($source, $format, $ffmpeg, $bitrate, $channel, $freq) { 
 
$cmd = "-acodec libmp3lame -ab $bitrate -ac $channel -ar $freq";
 
$org  = $source;
$wrong = array("å", "ä", "ö", "Å", "Ä", "Ö", "!", " ");
$right   = array("a", "a", "o", "A", "A", "O", "_", "_");
 
$new = str_replace($wrong, $right, $org);
 
 
  exec("$ffmpeg -i $new $cmd {$new}.$format"); 
 
   
     if (file_exists("{$new}.$format")) {  
      
      return array('audio' => "{$new}.$format");
   
   } else {
   
      return false;
      
   }
} 
 
 
///// SKICKA/LADDA UPP ///// 
if (isset($_POST['submit'])) {
 
$audio  = $_FILES['audio']['name'];
$wrong = array("å", "ä", "ö", "Å", "Ä", "Ö", "!", " ");
$right   = array("a", "a", "o", "A", "A", "O", "_", "_");
 
$new = str_replace($wrong, $right, $audio);
 
$path = "ljud/$new";
 
 
   if(move_uploaded_file($_FILES['audio']['tmp_name'], $path)){
 
 
      $type = "mp3";            // format att konvertera till
      $ffmpeg = "ffmpeg";       // Sökväg till mappen där ffmpeg ligger
      $b = "128k";              // Kvalite på ljudet: 96 kb/s
      $c = "1";                 // Kanaler (1=mono, 2=stereo) 
      $f = "16000";                 // Sample rate
 
      
      $convert = convert_audio($path, $type, $ffmpeg, $b, $c, $f); 
 
         // Lyckades konverteringen?
         if ($convert) {
         
            $msg = "<b>Ljudfilen ( ". basename($convert['audio']) ." ) konverterades utan problem!</b><br />
              Bitrate: $b | Kanaler: $c | Sample rate: $f<br /><br />";
         
         } else {
         
            $msg = "NÃ¥got gick fel!"; 
         }
}
   
   echo $msg;  
} 
///////////////////////////

PHP:

The code above, converts/encodes all audio formats to .mp3 and changes bitrate, sample rate and so on.

Now i want to convert/encode 2 .mp3-files (of the same file), during upload.
One with low bitrate (demo/exampel), and another with high bitrate.

 

I changed it to this:

if (isset($_POST['submit'])) {
 
$audio  = $_FILES['audio']['name'];
$wrong = array("å", "ä", "ö", "Å", "Ä", "Ö", "!", " ");
$right   = array("a", "a", "o", "A", "A", "O", "_", "_");
 
$new = str_replace($wrong, $right, $audio); 
$path = "ljud/$new"; 
 
 
   if(move_uploaded_file($_FILES['audio']['tmp_name'], $path)){ 
 
      ///// LÃ…G ///// 
      $type = "wav";            // format att konvertera till
      $ffmpeg = "ffmpeg";       // Sökväg till mappen där ffmpeg ligger
      $b = "64k";               // Kvalite på ljudet: 96 kb/s
      $c = "1";                 // Kanaler (1=mono, 2=stereo) 
      $f = "16000";                 // Sample rate
      
      $convert_low = convert_audio($path, $type, $ffmpeg, $b, $c, $f); 
      /////////////// 
 
      ///// HÖG ///// 
      $type = "mp3";            // format att konvertera till
      $ffmpeg = "ffmpeg";       // Sökväg till mappen där ffmpeg ligger
      $b = "192k";              // Kvalite på ljudet: 96 kb/s
      $c = "2";                 // Kanaler (1=mono, 2=stereo) 
      $f = "44100";                 // Sample rate
      
      $convert_high = convert_audio($path, $type, $ffmpeg, $b, $c, $f); 
      ///////////////
} 
}

PHP:

Now i can see that two files are created, one .mp3 with high bitrate and one .wav with low bitrate.
So far so good.

But a third .mp3 is also created, with low bitrate.
Why is that?