Ah, been there!
I had a huge wobble about DS1 being possibly 'offered' double not triple science as I really think we all know he needs triple. I did loads of research and still didn't really get to the nub of the matter but I learned lots along the way, for instance:
Our comp doesn't offer "core, additional & further additional science"; the Head of Science said it was because 'employers find it confusing, sometimes it's not seen as 'proper science' to the outside world, and if a DC is capable of this style of triple, the should be doing all 3 as separate subjects'.
So the choice is double "core & additional" or triple "physics, chem & bio". Unfortunately, both options take 2 GCSEs options, ie the triple is fast-paced. There's no option to do all 3 as 3 options which is what would suit DS1.
Left, right and centre (on MN, mainly!) I was 'assured' double is regarded as being every bit as good as triple
, however, most of the people stating this only had the option of double at their schools (therefore might have walked triple as well, had it been an option!), or had DC who were excellent 'all-rounders' who wanted to demonstrate great linguistics with 2 MFLs, great musical ability with music, art & drama GCSEs, great at humanities, doing history and geography, for instance, thus didn't want the 'burden' of triple science as well as they didn't feel they needed it.
There is an issue of the 'weaker' science bringing down the overall grade in 'double' which can't happen in individual triple subjects.
Then the horse's mouth (a science 'A' level tutor at a sixth form) told me he noticed his 'double science' GCSE takers did struggle to bridge the 33% lack of content when compared to his individual 'triple science' takers.
So DS1 is doing triple as individual subjects.