Dang, that is a blue one! Do you know the name of the cultivar?
Scots can double flush if you cut the shoots before they're hardened off. That's a stress response and I think I can explain it: The plant produces a huge bunch of auxins that it uses to elongate shoots and needles. It stores that stuff until it's needed, ideally when producing this years growth. If you cut a bunch of that growth off, there's still enough auxin left to produce new shoots. Since it's not going to the new shoots anymore, buds on the ends of branches are getting all of it and if the levels are high enough, you'll get a second flush.
A couple years ago a lot of people seemed to do that trick. I remember a thread about it. If memory serves me right
@M. Frary told me that it's not something you want for the longer term because it's both unreliable as well as a waste of good energy.