If you want the navbar buttons to display at the top and the bottom, but only want the breadcrumb and login parts to display at the top then you could go into the navbar template and grab the code just for the navbar buttons and copy it to the bottom of the showthread template where you want it.
And, just forget the part I mentioned about replacing $navbar in the 'showthread' with the breadcrumb and login part. The top navbar/breadcrumb/login would then display as normal, but you'd have the buttons on the bottom as well.
You'd be looking for the part in the navbar template
from:
Code:
<!-- / nav buttons bar -->
to:
Code:
<!-- / PAGENAV POPUP -->
</if>
And, you'd want to paste that into the 'showthread' template wherever you'd like the bar to display. I find it helpful to keep an unedited copy of the template along with a working copy so you can just paste them in really quick while testing.