Egyszeregy (1978)

When his overweight son born, the ludicrous daddy, who expected to have twins, still register him officially with two names, Péter and Pál. The grown-up son lives double life, one of his ego kind and polite, married a petite blonde and has 2 daughters, the other ego rude to others and drink a lot, married a pudgy brunette and has 3 sons. Everyone truly believes they are twins, who just never meet. His two different personalities help each other for a good while, but one day the threads are completely tangled.