The 'Add Other Evidence' wording is confusing. It should be changed to: "Add Attachments" with the text changing to "Add/Remove Attachments" once one or more attachments have been added to the cell.
Note that the page for doing the attachments says "Add Attachment" already.
SAK-13838 provides a more thorough revamping of the user interface, which should trump this request, whenever implemented. But this is a simpler first step.