I forgot where a certain groups setting is...?
Using Jamroom
I don't remember creating 'jrGroups_item_detail.tpl' when first working on your site, but that isn't to say that I didn't. Have just searched your skin templates and can find no evidence of it being called so likely it is redundent, but what I's do is rename the template to 'xxjrGroups_item_detail.tpl', say then see if anything on the site breaks. If after a few days there is no reported problem, assume its ok to delete it, or maybe just leave it - its doing no harm and not taking much disk space!!