Don't know what the policy is about re-marking, but don't forget that the 120 is a Standardised score and not a raw score, so it's quite likely the raw scores in the 2 tests were quite different. This would certainly be the case if other candidates found the 1st test easier as well.
One suggestion to follow up with your appeal is to find out from the LEA what the Statistical margins of error were for the 2 exam and use this in your Appeal letter. Ettiene may be able to help with the words on this.
If you weren't already aware, the Age Standardisation process used by all LEAs and 11+ exam bodies is a statistical process which results in candidates being given an age adjusted standised score which is directly related to an overall test percentile. As it is a statistical process it is subject to errors which the exam marking body must have assessed. Given that you child achieved 120 & 120 and missed by 1 point in each case, there is a very good chance that your sons scores were within the margins of statistical error. I would formally ask what the margin of errors were for the test and include that in you case - possibly quite high up the list.
As an example, I have quoted a section from the recent Gov QCA KS2 Test threshold tables document for the 2005 test:-
Any scores derived from a short test are subject to some margin of error. A margin of error does not mean pupils have been assessed incorrect ly. It is simply a statistical estimate, based on the fact that tests can only sample the particular area of learning which they assess. To indicate how wide this margin of error is likely to be, a '90 per cent confidence band' has been calculated. This means that you can be 90 per cent sure that the puplil's true score lies within the confidence band.
For the 2005 KS2 SATs the confidence bands were plus or minus 8 marks, 5 marks and 9 marks respectively for the Reading, Matha and mental maths tests.
Hope this helps
Best of luck on appeal