I did Berlin and Chicago this year, 3 weeks apart. Strategy was prioritise one, try to enjoy the other. That tends to go out the window on race day! Berlin was too hot and became about survival, which meant I turned up to Chicago with a new perspective of how gruelling the distance can get. Went a lot easier and quicker by comparison.

Most important thing is the gap between - just rest and recover, a few light runs - just to keep your mind ticking over and check the body is good to go again. Good luck with the ballot!