It's not uncommon for the same raw score for children with a 3 month age difference to have the same standardised score, although typically 2 months would probably be the norm.
If you want some examples of an actual Age standardisation results table against raw scores, take a look at the Key Stage 2 level Threshold tables and Age Standardised scores
for the last few years' tests on the QCA Web site:-
The LEA should provide the standardisation table in this case; I obtained the results a few years ago for the KE Foundation after I wrote in requesting it under the Freedom of Information Act.
I also know that last year the LEA were quite helpful in providing evidence to an Appeals parent in the form of a full analysis of the results (after standardisation unfortunately)
Hope this helps