A real matchworn jersey or just a fanshop jersey?
Firstly the differentiation is not between an original jersey and a fraud but between a jersey from an obligatory game (a jersey of a professional football player) and a jersey that has been bought in the fanshop. In rare cases these have been the same. E.g. at the world cup in 2006 in which Addidas let them play with Climacool jerseys to be able to promote the jerseys further.
Moreover, the same jerseys have also been worn in the German Football league (Bundesliga). These have been worn in the German football league as well as they have been sold in the fanshop. A good example that can be named is the SV Werder Bremen in 1997/1998 with its sponsor O-Tel-o which jerseys have been produced by Puma.