It is entirely at your discretion whether you wish to share the scores with a later tester, but please, please, please let them know that prior testing has been done, and the tests that have been given, especially if it is within two years of the last test, as a premature re-administration of the same instrument will invalidate the second administration, which clouds the picture, and may result in wasting time, money, and aggravation.
As an evaluator, I much prefer to have the results of prior testing; I think all data contribute to my understanding of a child. Changes in performance can be just as informative as consistency, especially in cases where 2e is suspected.
