Hello and welcome to the forum. Please can you let us know what you were feeding before the Guru and if your dogs were always hungry when on that food? Did you have to give more than the RDA with the previous food?
With regards to you giving half as much again of the recommended allowance, what are you basing the latter on? Normally the company advise 1% to 1.2% of the dog's body weight. Also, are you weighing the food or using the measuring cup?
Scrounging for food is a real headache - I have it with my three. Unfortunately they put weight on easily so I have to watch their intake. There are some dogs that never seem to be sated and if you are sure that they are getting all they need and are healthy, all you can do is stick them out.
FWIW, my (scrounging) dogs are on cold pressed food and I give them three smaller meals a day - I don't know whether this is the right thing to do but it seems to be better for them. My theory is that cold pressed is digested more easily than kibble and possibly leaves the stomach more quickly so that is why I feel it may be helpful. However, that is just a personal opinion. In the past, because cold pressed food is so dense I have found the small amount a problem with my dogs but it is something I have learned to cope with. If I gave them kibble they would probably be the same. Currently they have 1% of body weight and I top up with various proteins - fish, chicken, sardines. Sometimes I substitute one of the meals with scrambled egg or raw complete. I find that all of these extras go well with cold pressed food. I also sometimes soak the nuggets as it takes the dogs longer to eat the food when wet. Slow feeders are also useful to make the dog take more time over it's meal.
As your dogs are doing well on Guru it is a shame to change food but if you do then let us know and we can try to help you select something suitable from the Dog Food Directory.The other thing that you could do is contact Guru customer service to ask their advice.
Edit - regarding the fighting, I have had that myself in the past. You may know what the flash points are, in which case you can perhaps take remedial action to prevent it. With my dogs I take the bowls up as soon as they are finished and I try not to let them go sniffing around after a meal. If I sense trouble, I separate them. They are not allowed in the kitchen when food preparation is going on and same goes for our meal times. It's a case of being one step ahead of them - not easy though.