[ghaff]

My state switched from 1 plate to 2 plates (admittedly a long time ago) and if you had an old single plate there was no requirement to "upgrade" immediately. I assume the same thing has happened elsewhere. I only upgraded when the car failed state inspection because the plate had become less readable.

[devilbunny]

We get fresh plates with every redesign - you might be able to steal a tax-year sticker from someone's mailbox, but after X years (think it's six) they're going to redesign and an old plate will be obvious. Regardless of how long you've had the old one, when the new design comes up, everyone (except those who pay extra for a "themed" plate, not just a custom set of letters/numbers) gets a new plate.