Custom Form of SharePoint-List: Prevent default DataFormWebpart to be added

I'm working on a SharePoint 2013-Solution which deploys a custom list with custom site columns and a custom form. In the list's Schema.xml I added following lines:

<Forms>
  <Form Type="DisplayForm" Url="DisplayVisitor.aspx" SetupPath="features\$SharePoint.Feature.DeploymentPath$\Visitors\DisplayVisitor.aspx" WebPartZoneID="Main" />
  <Form Type="EditForm" Url="EditVisitor.aspx" SetupPath="features\$SharePoint.Feature.DeploymentPath$\Visitors\EditVisitor.aspx" WebPartZoneID="Main" />
  <Form Type="NewForm" Url="NewVisitor.aspx" SetupPath="features\$SharePoint.Feature.DeploymentPath$\Visitors\NewVisitor.aspx" WebPartZoneID="Main" />
</Forms>

Inside the NewVisitor.aspx, I have a DataFormWebPart which XSL definitions etc. In general, I followed the description on this article: http://ift.tt/1o4Awhg

The deployment works and the form is successful loaded when adding a new item, but after my DataFormWebpart, which is displayed the way it should, the default list form with all other columns is added automatically.

When inspecting the page, I can confirm that a second webpart is added automatically during deployment, but this should not happen.

How can I prevent SharePoint to add a default list form to the page, so that my defined DataFormWebpart is the only one form which is displayed?

Thank you for help!