of course its doing your head in!!!
I'm not sure what I can say to help - except that it will help.
In the meantime, can you find ways to help distract them both.
At the grand age of 11 months I have suddenly discovered my son likes a dummy, I only realised cos he would suck on things (blocks etc) so I offered him a dummy that I had in the drawer from when his brother was a baby and he loves it, he was loud in the car, now he is quiet.
Mealtimes we get a bit of shouting, whining if he is tired and hungry, I try to carry on regardless and make more of a fuss of DS1 - you could try and change things completely, maybe not sit round the table put a mat on the floor indoor picnic - sometimes I find just changing the routine or doing something different for a few days is enough to break the pattern.
Other than that - remember the mantra 'this too is a phase it WILL pass'