Fill bib1 and bib2 with the two bib file content, then the merged bib content will appear in the third text box. The merged bib text is automatically copied into OS clipboard.
When removing duplicated items, each item is identified by the first line, which usually contents the citation label. An example is:
@inproceedings{cite2021label,
title={...},
author={...}
}
bib1:
bib2:
merged: