Response.Redirect - Posts Back To Self Before Redirecting?

Does a response.Redirect first postback to the page that's calling the redirect before actually redirecting? I don't think so but my debugging is showing me that it is.

I can see it doing so and that causes me a problem. The problem is this:

1) My page has an asp.net button on it
2) When the button is clicked, the page posts back of course. Then the following is called in the event handler method for that button:

Response.Redirect("Checkout?frpp=1"), true);

3) But I notice that when the redirect is called, it first goes back and hits the page load for this page, the page that's doing the redirecting. Well that is causing me problems because it's calling code that I don't want it to be calling again such as this:

if (!IsPostBackl)
ShowOrderItems();

so it's like I'm doing a 2nd postback:

first postback happens when you click the button, hits the event handler, runs my handler method which calls the Redirect. Redirect is called but it's doing another postback to the same page here..why?