I am trying to invoke a method or content using multiple submit buttons but it says "server error /" in MVC

See more:

C#

in xyzsController.cs

public ActionResult test4()
    {
        return View();
    }
 [HttpPost]
     public ActionResult test4(string submit1 ,string submit2)
    {
        if (!string.IsNullOrEmpty(submit1))
            {
            return Content("test1");
        }
        else if (!string.IsNullOrEmpty(submit2))
         { return Content("test2"); }
        else
            return View();
    }

In test4.cshtml

@model xyzz.Models.xyztable
@{
    ViewBag.Title = "test4";
}

<h2>test4</h2>

@using (@Html.BeginForm("test4","xyz",FormMethod.Post))
{
    <input type="submit" name="submit1" value="submit1" />
    <input type="submit" name="submit2" value="submit2" />
}

What I have tried:

the view is displaying both the buttons but on clicking the button it says

Server Error in '/' Application.

Requested URL: /xyz/test4