title: MVC Action getting called twice?
body: <p>I am using Asp.Net MVC3, for a project.</p>
  
  <p>In one of the page, I  am using MS Charts. In View I have a Image which shows the chart as follows:</p>
  
  <pre><code>&lt;img src="@Url.Action("RenderCharts", "Home", new
                   {
                       XAxisColor = ViewBag.XAxisColor,
                       YAxisColor = ViewBag.YAxisColor,
  
                   })" alt="Charts" runat="server"  /&gt;
  </code></pre>
  
  <p>I have 2 CheckBoxes, which is used to change Chart Axes Colors. When the checkbox is clicked, page is submitted and checkbox status is stored and based on that Chart is rendered:</p>
  
  <pre><code>bool XAxisColor = (@ViewBag.XAxisColor) ?? true;
  bool YAxisColor = @ViewBag.YAxisColor ?? false;
  
  @Html.CheckBox("chkXAxisColor", XAxisColor, new { @Id = "chkXAxisColor", 
                         onClick = "this.form.submit();" })
          X Axis Color
  
  @Html.CheckBox("chkYAxisColor", YAxisColor, new { @Id = "chkScatter", 
                        onClick = "this.form.submit();" })
          Y Axis Color
  </code></pre>
  
  <p>When first time the page is loaded, <strong>RenderCharts() Action</strong> gets called and Chart is rendered.
  But when i Click any of the CheckBox, <strong>RenderCharts() Action</strong> gets <strong>called twice</strong>.</p>
  
  <p>I could not understand this issue. I have created a sample Application which can be downloaded from here <a href="https://www.dropbox.com/s/ig8gi3xh4cx245j/MVC_Test.zip" rel="nofollow">https://www.dropbox.com/s/ig8gi3xh4cx245j/MVC_Test.zip</a></p>
  
  <p>Any help would be appreciated. Thanks in advance.</p>