Well, when I try out my expression here:
http://www.regexlib.com/RETester.aspx it lists 15 matches. So, I figured my code (below) was doing the same thing.
const
string LAST_ON_ORDER_PAGE_NO = @"/cdvd\+on\+order/1,1,(\d+)";
Match match = Regex.Match ( pageContent, LAST_ON_ORDER_PAGE_NO, RegexOptions.IgnoreCase );