jqplot曲线图问题，求助，谢谢

[dengyulong]

定义如下：
$.jqplot.config.enablePlugins = true;

var line1 = [
["8/1/2013", 120.21], ["8/2/2013", 116.52],
["8/3/2013", 115.32], ["8/4/2013", 119.26],
["8/5/2013", 118.26],["8/6/2013", 117.65],
["8/7/2013", 111.46], ["8/8/2013", 116.28],
["8/9/2013", 121.86], ["8/10/2013", 119.36],
["8/11/2013", 129.76], ["8/12/2013", 136.76],
["8/13/2013", 138.76], ["8/14/2013", 133.76],
["8/15/2013", 149.76], ["8/16/2013", 162.76]
];
plot2 = $.jqplot('lineChart', [line1], {
title: 'Google, Inc.',
series: [{
label: 'Google, Inc.',
neighborThreshold: -1
}],
axes: {
xaxis: {
renderer:$.jqplot.DateAxisRenderer,
rendererOptions: {
//tickInset:0.5 表示在图像2边再插入一个网格，当数据点太靠边时可以设置此属性
},
tickRenderer: $.jqplot.CanvasAxisTickRenderer,
tickOptions: {
angle: -30,
formatString : '%Y-%m-%d'
}

},
yaxis: {
renderer: $.jqplot.LogAxisRenderer,
tickOptions:{ prefix: '$' }
}
},
cursor:{
show: true,
zoom: true,
showTooltip:false,
constrainZoomTo: 'x',
looseZoom: true
//showVerticalLine:true,
//showCursorLegend:true
//cursorLegendFormatString
}
});

问题描述： 在使用缩放功能时，发现x轴刻度存在重复，怎么解决这个问题？