Same problem with my 2 boys! Tonic always finishes first because Gin eats slower. Tonic is more dominant and when he goes to Gin his plate, Gin will just walk away and let his brother eat the rest...
What I do now:
I always place 2 plates (or bowls), with a bit of distance in between, on the ground. On one plate I spread the wet food all over the plate so it's more hard work to eat
Then I sit next to them and wait till Tonic is finished. When he tries to go to the other plate, I gently push him away or block his sight with my hand. I kept on doing this the last couple of weeks and he 'sort of learned' that he should wait for his brother to finish too. Right now he only tries to steal food ones at every meal!
I know it's not always possible to sit next to your cats while they eat...
I really want to make sure Gin eats enough. I just started feeding raw and they are only 3 months old, so I just sit there till they are both done and feeling ok. I'm overprotective