One of the reasons for repro decals, of course, is so that a person can take a legitimate bike, repaint, and put the original brand decals back on.
Unfortunately, for one reason or another, some people will put either the wrong model decals on a bike, or wrong brand decals.
The person may just do it just for personal use, then the bike works its way into general market.
If you post photos, people on this board will help confirm what you have.