Board up the bars... Ive had to do this with all three boys as they all fight for my attention, to the point that my TB will throw himself against the wall between him and the other horse, the noise being horrific, which also echos in the barn! its very early days for you and as horrible as it is, there needs to be a pecking order established between your two..... It will sort itself out..... Chin up.... you do this cos you enjoy it!
Can't add anything to the excellent advice given by Shilasdair, you need to be top horse not them!
What are they like when out int he same field, do they eventually stop fighting?
i have two who have been fine all summer but now theres not as much grass one of them is grumpy and pulls faces at bringing in time. be firm i think winter brings out the worst in them as my warmblood is totally laid back normally.