If you are using Acrobat, you will need to tell the Acrobat driver to prompt for each PDF file name, or else Acrobat will overwrite the same PDF file with each borehole log. Since this is a particular Adobe setting, we cannot overcome the file name prompt when printing multiple logs.
You might alternatively consider using File | Export | Graphic or File | Export | Multiple Logs to export to a vector PDF file. Exporting to a vector PDF will generate a single PDF of all pages of all logs.
Updated: October 4, 2016