A form doesn't need to be tied to the controller which built its view. You can post to whatever you want:
@using (Html.BeginForm("SomeAction", "Home"))
{
I'll post to the Home controller.
}
@using (Html.BeginForm("SomeOtherAction", "Security"))
{
I'll post to the Security controller.
}
This just renders regular forms, so:
<form action="/Home/SomeAction">
</form>
<form action="/Security/SomeOtherAction">
</form>
This is one of the many many things that ASP.NET MVC got right and WebForms did not. If you tried to post to a different aspx page in the WebForms world, it would not be so easy.