As can be seen here, when an OCLC or PMID is found, Citoid adds not only this identifier, but an URL https://www.worldcat.org/oclc/<$OCLC>/https://www.ncbi.nlm.nih.gov/pubmed/<$PMID> to the citation template as well. This is redundant. A web link should only be provided if it points directly to the fulltext of the resource.
Weblinks from OCLC/PMID/DOI can be generated and managed much better by the citation template used.