A fair experiment is fair wheras an accurate experiment is more accurate.
LOL Joke. The latter simply means the results are to a higher degree of.... accuracy e.g instead of to 5, the result could be 5.1235
However a fair experiment is a test carried out under fair conditions.
If testing more than once during the experiment you have to be sure that things remain at the same level i.e.
Amounts of reactants
Time must remain the same..