Html.RenderPartial and Ajax.BeginForm -> Submit is called twice

Don't include scripts inside your partial views! They should go the your "main" views or your _layout.cshtml.

Your problem is that you have included the jquery.unobtrusive-ajax.min.js twice in your page. Once in your Create partial and once somewhere else. Because if you include that script multiple times it will subscribe on the submit event multiple times so you will get multiple submit with a single click.

So make sure that you have include that script only once in a page. So move the jquery.unobtrusive-ajax.min.js reference into your index view.