If there is any way of feeding them in separately enclosed places, this would be the easiest solution to begin with. Is it possible to keep one locked in the coop and allow one out to start feeding first before letting the second one out.
Try and observe which is the more aggressive of the two mothers and feed her first. By reinforcing the natural pecking order, it may help alleviate squabbles.
If you scatter the food into two areas, as opposed to over a large general area and place one chicken in each area with a reasonable gap between the two areas, it will make each chicken more reluctant to leave her food to go chase the other chicken from another pile of food, as she risks losing her food pile.
If possible stand between them while they eat, you can be a human fence and referee in the middle of their feeding escapades. You can use your voice to praise or scold them, you seem to have a close relationship with your chickens and they will get the idea of approval and disapproval from you. Whilst this, on it's own would have little effect, it will improve your communication with them and increase your overall bond. As mentioned in an answer to How do I make my chicken overcome his fears?, animals respond to how they are handled.
Another thing is to try feeding them more regularly or providing more feed. If they are going a bit hungry this will increase the likelihood of squabbling over food.