New redirect format in IIS7.5?

A couple of months ago, I noted that some of my Classic ASP apps are redirecting in a strange way. Where as previously a file would redirect fromdefault.asp to page.asp (assuming the user was logged in - using a cookie), now, there redirect looks likedomain.com/page.asp,page.asp which of course throws a 404 error, because that "page" does not exist.

The redirects are usually done by using a Response.Redirect.

Is this a new config that needs to be done to prevent to change this redirect format?

Thanks