Yes, that will be it.
The first layout has the number 1, if you would have a total of 3 layouts, then number 3 is the highest number you can go to.
The problem of counting 2x per level could be that the condition for counting up ist still true when entering the new level. Unfortunately, my pc is broken-down, and this 11-year old antique computer I have to use until my pc is repaired refuses to install Construct, so I can't look into the cap.