Cloned plate? Should I do anything?

[someday]

I'm thinking about getting a Suzuki Swift Sport so when I saw one trying to get out of a side street today I let it out. It was the latest shape (Mk 3?) which I think was launched in 2010 and the Sport in 2012, so it was a bit strange to see it on an 09 plate. I followed it for a while thinking maybe it has his initials on it, I realise you are allowed to make a car look older than it is and he turned off and I thought nothing more of it.

Then this afternoon driving home I noticed a previous shape SSS, same colour - red, parked up with I'm almost certain, the same number plate. Should I put a note under his wiper tomorrow saying his plate might have been cloned? The 2 cars were within a couple of miles of each other so maybe there's a perfectly legit reason like he's in the process of putting the plate on his new car or something.

Reg is LG 09 OGK.