How to find duplicate values ​​and save only these rows?

Question

I check a huge list of Open Office Calc for several values ​​in column C.

I have a file like this

  Abc
 jan 1 Joop 35.90
 jan 1 Kees 80.10
 jan 2 joep 79,99
 jan 4 Kip 14.88
 jan 4 Roel 15.66
 jan 8 Riep 35.90
 jan 9 Jaap 15.66

I would like to find all rows that have a value in column C, which is a duplicate of another cell from C (so ignore columns A and B). I would like to get the result as follows:

  Abc
 jan 1 Joop 35.90
 jan 4 Roel 15.66
 jan 8 Riep 35.90
 jan 9 Jaap 15.66

Can you guys help me achieve this?

Answer 1

Place this formula in column D and copy it. Every second double entry will be marked 2 (or more), the rest - 1.

Copy column D, then paste in the special text (delete all other marks) using the same data in column D.

Now the whole formula has been converted to fixed data in column D.

If you only need to perform this cleanup once, you can put 1 in E1 and drag it down to the top drag point of cell E1 to create a list of sequence numbers (1,2,3,4 ..).

Then sort the entire range in column D.

Delete all rows with 2 in column D.

Then apply the entire range in column E (source sequence numbers)

=COUNTIF(C$1:C1;C1) 

Another option is to use a standard filter

Select the No duplication option, but this is just a filter, the data still remains on your sheet.