i noticed i had an ebuild which accidentally inherited the same eclass twice. would be nice if repoman had noticed before i did.
pkgcheck has DuplicateInherits now, fwiw
repoman support has been removed per bug 835013. Please file a new bug (or, I suppose, reopen this one) if you feel this check is still applicable to pkgcheck and doesn't already exist.
pkgcheck has DuplicateEclassInherit.