Canadian Rainbirds are correct. You have to have the vehicle with you when you cancel a TIP. This applies to everything that requires a TIP and the term length of the TIP does not affect this law. For 6 month TIPs this means you should turn it in EVERY TIME you come back north unless you want to wait for 4 - 6 months to get a TIP canceled. For an RV you should cancel the 10 year TIP if you even think you might want to sell/trade the vehicle before your next trip. And remember, you can only have one car TIP and one RV/Boat TIP at a time, so you will have to spend that 4-6 months outside of Mexico (or inside Mexico but without the subject vehicle).
The 'originals only' rule has always been there, either you've just been lucky or your copies look a lot like originals.