Find something that they both like to do that is an alone thing......like reading a book, coloring, playing a game of some sort...........maybe tinker toys, dolls that you can put clothes on..........something that is a one person thing.....
Before you go do the dishwasher, or whatever, sit down and get them started on something to do.....then say, you are doing great, keep it up, I'm going into the kitchen.........if they follow, tell them to go back and play you are fine.......
You might even explain to the 6 year old that you need some alone time....while you do a chore..........and let them know it's ok to be in the living room while Mommy is in the kitchen or other room......if they have separate bedrooms, you might even want to give them a bit of time in their room alone....Just a bit of space....
Be glad they want to help, one of these days you will get attitudes for asking them to help!!!
They will be fine......good luck.....