A man in a dark jacket stands next to a man dressed in brown reaching down into a bag.
Two men in dark clothing, one is reaching into a bag.
One man is dressed in a "dark" color, while it's said that the man in "brown" (a dark color) reaches into a bag.
Both sentences describe two men, one of whom is reaching into a bad.
Two man are wearing dark clothing, one is wearing a dark jack and the other one in which he is standing next to is wearing brown which is another dark color.