<input type="submit" name="submit" value="<val>">

if(submit == "button1") {
  RedirectToAction("Page1");
} else {
  RedirectToAction("Page2");
}

@using (Html.BeginForm("Test", "Home", FormMethod.Post))
    {

        <input type="submit" value="Go 1" name="go-1" />
        <input type="submit" value="Go 2" name="go-2" />
    }

[HttpPost]
    public ActionResult Test(FormCollection collection)
    {
        if (collection.AllKeys.Contains("go-1")) return View("Page1");
        if (collection.AllKeys.Contains("go-2")) return View("Page2");
        return View("Index");
    }

public ActionResult Process()
{
  // do processing

  // redirect to page 2
  return this.RedirectToAction("Index", "Page2");
}

@Html.BeginForm("Process", "Page1", FormMethod.Post)
{
  <input type="submit" name="button" value="Submit" />
}

@Html.ActionLink("Redirect to Page 2", "Process", "Page1")