Maths A level= physics A level. Maths has a large role in both chemistry and biology. However, it could be argued the maths is unavoidable.
But still, biochemistry is another example of overlap without maths. Should people with all science + maths subjects be treated the same as those who do further maths?
And how is that too much overlap? If you can't apply those skills from other sciences - most of which is GCSE level, except for using log stuff in Chemistry and even then it's only AS level being one of the easiet topics on C2 - then you shouldn't do any sciences altogether.