Do you buy two of everything when the kids are a year apart?

My son and daughter are about a year apart and right now every fight is over one particular object. This week it's a yellow digger. Last week it was a steel tumbler from the kitchen, of all things. My mother says buy two of everything, problem solved. Our caregiver says then they'll fight over who has the better one. I leave for work before 7, so I only get the evening rounds, but those are loud enough 🙂 Did buying doubles help you, or does the fight just move to the next thing?