Just something else you can also do if joining that many tables is all new to you.
You can join say the first two tables then check the output and then another and then check again until you
spot the join that is introducing the duplicates/rows you want excluded.
This would also give you some understanding of the data you are querying which is also what appears to be lacking here.
If you are, however, able to provide data which would be representative of the problem you are actually having then, of course, as has already been suggested go ahead and do so.