If you suspect someone else has a car that looks identical to yours and is causing you problems.... why not change something about your car?
I mean, I'm not talking major stuff, but something to differentiate it. Like... new rims, or a bra (ick), or a couple of unimportant stickers on the windows. You know, like K&N or something, not something to draw unwanted attention and increase the risk of theft. No giant JL or Kicker stickers, I mean.
I dunno, there are easy cheap ways to set your car out a little bit, aren't there?