Its not illegal. Actually I think its a good idea to be able to fly in/from either seat.....well not rear ones of course. If 2 pilots are flying together and have experience in either seat in any GA aircraft then either can be PIC in whichever seat, taking-off, flying S&L or landing. And always useful in an emergency.
I'm hoping to get some C152 & C150 RH experience to add to some C337 RH seat I have.