Ajax Post Submit Function Submits Twice

I've tried many of the other solutions to this problem on SO, and elsewhere, but I can't seem to prevent my form from submitting twice. Here is the code that I'm currently having this issue with:

jQuery Code

$(function() {
  var additemtoform = $('#additemform');
  var handleData = function(responseData) {
    if ($(responseData).find('#repitems').length) {
      var replacement = $('<div />').html(responseData).find('#repitems').html();
      $('#test').html(replacement);
    } else {
      additemtoform.submit();
    }
  };

  $("#additemform .addbtn").on("click", function(e) {
    e.preventDefault();
    $.ajax({
      type: 'POST',
      url: 'WebCatPageServer.exe',
      dataType: 'html',
      cache: false,
      data: additemtoform.serialize(),
      beforeSend: function() {},
      success: function(data) {
        handleData(data);
      },
      error: function() {
        alert('error');
      }
    });
    return false;
  });
});

If I remove the submit in the callback, then the form doesn't submit at all. So, what am I missing?

Thanks!

Update

Note that this code is update from the original per Habbe's suggestion below. The same issue with the double submit persists, however.

HTML Code (Generated)

                <td><a href="WebCatPageServer.exe?PROD_FULL&ProdInfo=00012000551">BRW2394746301</a></td>
                <td>239-47463-01</td>
                <td>Gas Valve Complete, Icon Natural Gas</td>
                <td> $207.32</td>
                <td>Available</td>
                <td>
                    <input name="Q1" tabindex="1" class="qtyfield" type="text" size="1" value="0" onblur="clickrecall(this,'0')" onfocus="Q1.select()" />
                </td>
                <td>
                    <input name="P1" type="hidden" value="BRW2394746301" />
                    <input name="M1" type="hidden" value="239-47463-01" />
                    <input name="D1" type="hidden" value="Gas Valve Complete, Icon Natural Gas" />
                    <button type="button" class="button lightgray smallrounded addbtn" value="Add">Add</button>
                </td>
            </tr>
            <tr>
                <td><a href="WebCatPageServer.exe?PROD_FULL&ProdInfo=00012000552">BRW2394746501</a></td>

                <td>239-47465-01</td>
                <td>Gas Valve Complete , Icon Propane</td>
                <td> $272.58</td>
                <td>Available</td>
                <td>
                    <input name="Q2" tabindex="2" class="qtyfield" type="text" size="1" value="0" onblur="clickrecall(this,'0')" onfocus="Q2.select()"/>
                </td>
                <td>
                    <input name="P2" type="hidden" value="BRW2394746501" />
                    <input name="M2" type="hidden" value="239-47465-01" />
                    <input name="D2" type="hidden" value="Gas Valve Complete , Icon Propane" />
                    <button type="button" class="button lightgray smallrounded addbtn" value="Add">Add</button>
                </td>
            </tr>
            <tr>
                <td><a href="WebCatPageServer.exe?PROD_FULL&ProdInfo=00012000553" style="text-decoration:underline;">BRW2334784505</a></td>
                <td>233-47845-05</td>
                <td>Pilot Assembly, Icon Natural Gas</td>
                <td>  $32.58</td>
                <td>Available</td>
                <td>
                    <input name="Q3" tabindex="3" class="qtyfield" type="text" size="1" value="0" onblur="clickrecall(this,'0')" onfocus="Q3.select()" />
                </td>
                <td>
                    <input name="P3" type="hidden" value="BRW2334784505" />
                    <input name="M3" type="hidden" value="233-47845-05" />
                    <input name="D3" type="hidden" value="Pilot Assembly, Icon Natural Gas" />
                    <button type="button" class="button lightgray smallrounded addbtn" value="Add">Add</button>
                </td>
            </tr>
        </tbody>
    </table>
</form>