图片向左滚动效果，为什么只有一张图片，却显示了两张


<div id="colee_left" style="overflow:hidden;width:500px;">
<table cellpadding="0" cellspacing="0" border="0">
<tr><td id="colee_left1" valign="top" align="center">
<table cellpadding="2" cellspacing="0" border="0">
<tr align="center">
<td><p><img src="http://www.alixixi.com/images/noimg.gif" width="100" height="100"></p></td>
</tr>
</table>
</td>
<td id="colee_left2" valign="top"></td>
</tr>
</table>
</div>
<script>
//使用div时，请保证colee_left2与colee_left1是在同一行上.
var speed=30//速度数值越大速度越慢
var colee_left2=document.getElementById("colee_left2");
var colee_left1=document.getElementById("colee_left1");
var colee_left=document.getElementById("colee_left");
colee_left2.innerHTML=colee_left1.innerHTML
function Marquee3(){
if(colee_left2.offsetWidth-colee_left.scrollLeft<=0)//offsetWidth 是对象的可见宽度
colee_left.scrollLeft-=colee_left1.offsetWidth//scrollWidth 是对象的实际内容的宽，不包边线宽度
else{
colee_left.scrollLeft++
}
}
var MyMar3=setInterval(Marquee3,speed)
colee_left.onmouseover=function() {clearInterval(MyMar3)}
colee_left.onmouseout=function() {MyMar3=setInterval(Marquee3,speed)}
</script>