I need to know if it is necessary to do more than one DNA fingerprinting so that the results obtained have greater relevance, or if only one is enough.
Normally, one DNA fingerprinting is enough. But if you wish to consolidate your experimental outcomes, 3 separated repetitions are the best that you can do to nail it once and for all.
There are a lot of criticism against DNA fingerprinting techniques. It is better to do it at least 3 times to confirm that the pattern you are getting is actually a stable one.