URL Rewriting - File Access

I was attempting to implement simple URL Rewriting using an HTTP
Module in asp.net with C# with an event on BeginRequest and powered by
a
Context.RewritePath. I got everything to work fine.

When I was using FileMon, I noticed that aspnet_wp.exe attempts 2 file
access for the file that's rewritten, and doesn't find it. I am
trying to rewrite html files and have configured IIS to use the
aspnet_isapi.dll. I have removed "check if file exists".

I installed a different ISAPI filter (Ionic) to test. I noticed that
with this, disk access is not performed.

Is there any reason for this functionality with using ASP.NET
Rewriting? Is there a way I can stop it? I'm kind of interested in
why this is happening from a technical standpoint.

Thanks for your thoughts.