Is Having Two Puppies From The Same Litter Bad?

i bred cockapoo puppies and have a buyer wanting two puppies. iv’e heard though that it’s bad to do that because they don’t have to love you because they always have each other.
also that they’ll never learn thier name because you’re always saying two, and if you yell at one the other thinks he’s being yelled at, resulting in them never getting trained.
any help??