This more likely than you think, likely enough, in fact, that it has already been confirmed to have happened in multiple countries [1]. The problem of fraud and data corruption is widespread enough that it is hampering longevity research [2][3]
[1] https://www.cremieux.xyz/p/the-blue-zone-distraction
[2] https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000148
[3] https://www.biorxiv.org/content/10.1101/704080v3