Pugs, you have misunderstood the nature of the KS1 tests. The levels reported are TEACHER ASSESSMENT LEVELS, from a whole range of work across the year. Children do also take 'a test', but if there is a discrepancy between the two levels, then the teacher assessment result is the one that is reported.
So it would make no difference which test your child took. If the teacher assessed her, on her everyday work, as a level 2, then she would be reported as a level 2, regardless of what test she happened to sit on one day during the year.
You can argue that the teacher mis-assessed her during the year, but to suggest that 'had she been able to access the higher level test she would have done better' is misleading at best - had her teacher assessment been a level 2, a level 2 she would have remained.
Teacher assessment levels are tied to what a child can actually do, over a period of time. DS was assessed as level 3 in maths in Year 1, for example, without ever sitting a test.
It is indeed an interesting question why her daily performance in class was so out of line with her performance in a different school - but it will NOT be due to some conspiracy related to tests and levels, just perhaps that she did not perform well day to day in that environment for some reason.