There are known, non-doctored 1 cent Euro coins with "two heads". They are quite rare, but they exist. I believe US dies for the obverse and reverse are not interchangeable (i.e., they are i-diot proof!).
There is only a directive about melting down cents and nickels, it has not been challenged in court, and I believe its unconstitutional. Courts have ruled consistently coins are personal property and you can do with them what you wish. Silver US coins sure as heck are melted all of the time, and they are still legal US coins. The treasury just put a rule in place to scare people to not melt cents and nickels to give themselves time to produce a replacement, since they knwo eventually these coins will disappear due to Grasham's Law. Coins you can do anything you want to, they are your property. However, defacing them and THEN trying to spend them can be illegal, since you are changing them back from your property back to coinage, and you have defaced them rendering their usefulness to zero. Chris