have (one's) bread buttered on both sides
To receive two separate benefits or advantages from a particular situation (which is often deemed to be unfair or unreasonable). You can't be on the voting committee and give yourself an award—you can't have your bread buttered on both sides!
have your bread buttered on both sides
If you have your bread buttered on both sides, you are able to benefit in two different ways in a way that people think is unfair. Now they have their independence and I wish them well but they must not be allowed to have their bread buttered on both sides.
have your bread buttered on both sides
be in a state of easy prosperity.