For the most recent versions, in my opinion, these two commands allow us to insert PDF files with the same functionality and very similar properties. I think using both is redundant. Maybe the "Import PDF" Button can be removed.
Yes, I am aware of it and I agree with you. The same goes for CAD and images files. My suggestion is not to remove the "Import" function, I mean to remove the button from the ribbon.
When we insert a PDF, CAD or Image file as a link we have the option to import it from the "Manage Links" dialog box. Maybe a single button can be used for each case and put the option to import it as a checkbox in the file search box. For example: 1 button for Link / Import PDF 1 button for Link / Import CAD 1 button for Link / Import Image