Does the PROSPERO registration prevent double review on the same topic?

The best journals request registration on the PROSPERO website for systematic reviews and meta-analyses, in an effort to improve the scientific quality and avoid publication of a similar review article some weeks later on another journal. However, two systematic reviews about a very rare disease were registered on the PROSPERO website and published in the same period. The authors consider that registration with PROSPERO website is necessary to reduce the risk of duplicating reviews, but its effectiveness is largely perfectible.