Author space has only one box to type in

I have had to manually add some references.In the author field there is only one text box to type in, consequently the surname and first name appear together.For imported references, there are two text boxes, one for surname and one for first name - though if I copy a citation with two boxes and try to add a second author, there is only one box to type in.How can I add a second text box to the author field?Any advice is appreciated.
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