I have two bicycles (OK, two bicycles with Look Keo pedals). One is touring bike with an ultegra triple crank (older, probably 2006 vintage) and the other one is a Roubaix SL2 with Ultegra 6750 crank.
I set the cleats on my shoes mostly using the touring bike since I also commute to work on it. I probably put 2/3rs of my total mileage on the touring bike. When I use the same shoes on the Roubaix with the double/compact crank, the cleats are slightly off. They are workable but they feel slightly off.

First question. Given that all other measurements (handlebar drop, size, seatpost, saddle height) are identical and both bikes have a Fizik Aliante installed, I am guessing that the difference I feel is due to the q-factor of the triple versus the double crank. Am I on the right track here?

Second question, can I shim the compact crank pedals by using stainless steel washers by about 2mm on each side so that the I minimize the q-factor difference. My pedals instruction manual says that up to 2mm shims on each side is OK.

Thanks for all your help.