For preprints hosted in repositories where an additional DOI is assigned, we are unable to merge the preprint with the final published version due to multiple identifiers. The preprint and final published version in this case are treated as two unique outputs in Altmetric. 

If the preprints and the final published version of the research output have the same DOI, Altmetric will be able to merge both Details Pages.

In rare occasions, Altmetric can merge a preprint with a published version if the preprint has another identifier than a DOI, for example an arXiv ID. In this case, the Details Page will displays the DOI of the final version, but with arXiv as the original publisher.

Currently it is not possible to merge from bioRxiv or medRxiv servers.