Feeding issues

Dinner went well.  Was able to feed both of them without the dogs going for the other bowl.
 
Problem:  Sofie wolfed down her food (because Penny was eating her dinner, and I'm sure Sofie thought her dinner was next seeing that she's not top dog) then barfed it up in the yard.  I put Penny in the people yard and let Sofie have the "seconds" if you will.
 
I cannot free feed here.  
 
So, do I feed them at different times and alone, or let her work out that I won't let Penny eat her food?  No food aggression, I was able to get her to sit across the kitchen and have her bowl at the same time Penny had hers.
 
When I put them both off to potty, of course when they came in, they both checked out each other's bowls with no incidence.  
 
Sofie needs to gain some weight.  She's at 2.5 cups twice a day of Solid Gold Millennium.  What do you think of switching her to Science?  I need to see if Petsmart carries that brand.  If not, I'll have to switch her.