The Magpul flip up sights being offered may not be "fake", but are likely Magpul's less expensive version because Magpul makes paintball accessories too.
The Magpul sights made for paintball usually come paired (front and rear sights) in a brown cardboard box with the Magpul logo on it. The true Magpul AR parts are not sold in pairs or in boxes, put in clear plastic hang bags, one to a bag.