You need a new column and assuming that the reference numbers are in column A

try in column b

b2:=if(countif(a:a, a2)1,countif(a:a, a2),"")
and then copy it down

that will highlight duplicates and then you can do an auto filter on it to
get them
--
Hope this helps
Martin Fishlock, Bangkok, Thailand
Please do not forget to rate this reply.


"charlie777" wrote:

I am checking through a document register. The register relies on the fact
that every document has a unique referance number but i have come across a
few duplicates. How do i check the rather large register for other duplicates
without doing it manually, and without having a specific referance number to
begin with.

thanks