A black and a white dog means "two dogs".
A black and white dog means "one dog".
Then what about black and white dogs?
Does this mean two things? "Dogs, each of black and white color" and "dogs of black and dogs of white"?
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Unfortunately the plural can designate either group: (1) bicolor dogs, and (2) black dogs and white dogs.
They can be disambiguated as follows:
black dogs and white dogs
black and white brindle dogs (brindle means several colors on the same dog)
dogs, both black and white,...