I don't have time to research this, but I'm skeptical.
Like many such stories I've heard over the years, this one requires the "prankster" to commit a crime. Whether you are tripping cameras or not, putting a fake tag on your car has always been easy to do, and it has always been illegal. So, great, you can pull a fast one on your rival...as long as you are willing to drive around speeding and running red lights in an illegally marked car.
Also, in the State of Maryland (where I live,) and every other jurisdiction in which I've received a camera ticket, the citation includes a photo of the event. Unless the car is identical, it would be easy to disprove the charge.
Even if the car was identical, it would often be easy to disprove the charge anyway, by showing that you were some place else at the time (work, school, etc.)
So, while it would certainly would be possible to do this, I think the requirements for success make it unlikely that it is widespread. Unless it was meant strictly as a joke, in which case the prankster wouldn't care that the citation is unlikely to stick. Otherwise, I call bullshit.
Oh, by the way...The Montgomery County Police said they have not seen or heard of this prank occurring but said they will keep an eye out for people committing the crime.