Search query string doubled parameter?

"/search?Q=computer&As=true&As=false&Cid=0&Isc=false&Mid=2&Pf=&Pt=&Sid=false" is this normal to have it like this As=true&As=false in one query string?

this is reproducible in demo site too

This is not a bug in nopCommerce. This is a design issue in ASP.NET (more info here). Anyway, please note that it does not cause any real issues because searching works fine as a customer specifies. That's why we use BooleanParameterName extension method in the Search.cshtml file.