Patients with duplicate medical records had a higher likelihood of adverse outcomes and a longer hospital stay. This was shown by a retrospective analysis of a large US health system. These patients were compared with patients who had a single accurate record. Duplicate records increase the risk of treatment errors. The study analyzed a large amount of data from practice. The main findings confirm the association between duplications and worse health outcomes. The problem affects patient safety in hospitals. Accurate records reduce the length of hospitalization.