Answer:
When a research is conducted and results are deduced, scientists tend to perform the experiments again and again to check if the results are similar each time. These multiple set of research again and again is important to check and prove that our results are authentic.
Sometimes, it might happen that there might be some other external factor due to which the results are occurring as seen. Re-checking of the results s important so that it might be made sure that no external factor is the reason of the shown results.