 duplication of references. We may forget that one particular reference would have been cited in the initial part of the document and again it would have been cited in the later part of the document. This is called as duplication issue and this duplication issue was previously sorted out by mainly desktop very effectively. Even today Zotiro is doing that effectively. When you click on this duplicate function, there are so many duplicates appearing in the reference list. So once you click that, it will ask for merging of two items. So if you again click that, those two repeated references will be merged and it will automatically reflect in the document. On the other hand, if you go to mainly reference manager, these duplicates are matched based on the DOI. But here in Zotiro and in previous mainly desktop, this was based on the matching of other details also, which effectively could match all the duplicates. So here the matching duplicate itself is not effective and even after identifying these two duplicates, here there is no option to merge that references. You can just identify these are all the repeating fronts in the list. So then you need to manually check whether this reference is appearing again in the list. So this duplicate option which is present here is going to be identifying the problem but not solving your problem.