I strongly advise you to report the results in a single paper. Each experiment standing alone might be sufficient to meet some imagined standard of "minimal publishable unit." However, one strong publication will do more good, both for your professional reputation and for the progress of your field, than two weaker ones. And, as you are aware, two separate papers with a big overlap in wording could raise questions about integrity in research.
If, despite this advice, you decide to pursue two separate publications, please consider producing them sequentially: first, a full report on one of the experiments, and then a much abbreviated research note on the other experiment, citing the first report as a reference that readers can consult for details of the design. Doing it that way would alleviate the concern about plagiarism, as the wording of the two papers would differ substantially and you would be explicitly acknowledging the first report as a contributing source of the second one.
It would be recommended that the full experiment be reported in one paper. Trying to publish in the second paper means you will have to add an extention or further a new variables and jusge it in the experiment.Unless that happens,writing one experiment in two papers is not recommended
i am doing medical experiment in 2 different populations (Races) . I decided to make each in a different study and make the required comparison ( between these to races and other races in the database) in the literature review and discussion section of each paper.
Moreover, i already fished the 1st study in one race and sent it to journal and now i am preparing the 2nd study in the 2nd race to send it for publication.
Thanks for the clarification. In that case, you are already well along the path of "sequential" papers that I suggested. You could write the second paper as an abbreviated research report, citing the first paper. If the first paper has not yet been published when you are ready to submit the second one, you could include the first report, in whole or in relevant part, as an appendix for use by the journal's editors and referees during their review of your second submission (explicitly stating that the appendix is not intended for inclusion in the published version of the second report). Or, if your first submission is not immediately accepted for publication, you could combine the results from your two experiments into a single, stronger paper. Whatever you decide to do, I wish you success in finding a suitable outlet for the publication(s).