is there a way from a asp.net-page code behind with "Request.Redirect()" or another method to redirect to the last page (like Javascript history back)?
You can check the Request.UrlReferrer
property, which will be set if the user has navigated to the given page from another one. This is nothing more than the HTTP Referrer header that a browser will set. This will be null
if the user navigates to your page directly.