Yes both the cases are on same issue, newspaper / magazine etc circulation certified without adequate examination & evidence.
In actual decided cases by court, sometimes they applied clause (8) and sometimes clause (7)
I think clause (8) which is specifically on collecting insufficient information is appropriate as Clause (7) covers all types of negligence.
In exam first answer as per clause 8 and then give alternatively it can be answered as per clause (7) also
Actually Q.6d is about not obtaining sufficient information to warrant circulation of magazine whereas Q.15d here auditor certified circulation newspaper or whatever based on mis report which is insufficient that is it amounts to gross negligence in giving his opinion