求助：如何使一个页面中的所有声音文件，只能点击播放两边！

原先播放一边的脚本如下，请问如何做成能播放两边的？
<!--
//加入全局变量：播放列表（playlist）
var playlist="|";

function playAudio(audioindex)
{
var file = audioindex;

//播放判断文件是否已经存在播放列表playlist中
if (playlist.indexOf("|"+file+"|")>=0)
{
alert("Sorry，听力录音只允许听一遍！");
return;
}
else
{
playlist+=file+"|";
}

var file = audioindex;
MediaPlayer1.ShowAudioControls = false;
MediaPlayer1.ShowControls = false;
MediaPlayer1.ShowTracker = false;
MediaPlayer1.ShowPositionControls = false;
MediaPlayer1.ShowDisplay = false;
MediaPlayer1.ShowCaptioning = false;
MediaPlayer1.ShowGotoBar = false;
MediaPlayer1.ShowStatusBar = false;
MediaPlayer1.Filename = file;
MediaPlayer1.AutoStart = true;
}

//-->
</script>