I meant that web.config setting is best, but if one wants to show both only at some pages, they'd set the both option at web.config and hide the pager at some pages using a custom theme for that page
however I think at theme you can't set an ASP.net control property like visibility for some control using its id, but the control needs to have a ThemeId (was called something like that) attribute set to be able to refer to it from a theme. Probably MS did that for security reasons. Of course could also specify CSS classes like pager-top and pager-bottom and hide from CSS with a custom theme for specific pages where you don't want both pagers if in web.config you opted to show both