How to find duplicate rows in gnumeric or Libreoffice calc

This a way you can hide and then remove duplicate rows (or 'records') in Libreoffice Calc

• Go to the worksheet that has the duplicate entries, and select 'Data' > 'Filter' > 'Standard Filter' (it seems to automatically select the data in the sheet that it will filter, you may want to do this manually beforehand).
  Then in the box that pops up, select the column (Field - entering multiple 'Fields' may be possible), and as the value(s) enter 'Not Empty'.
  Then under the 'Options' pop-down menu, select 'No duplications' - you may want to select other options like 'Case-sensitive', 'Copy results to', etc as well.

• It should then filter the data, and hide any duplicate records. You can copy this to a new worksheet if you want to have the dataset without duplicates (instead of the dupes just being hidden).
  
  You can reset the filter if necessary by going to 'Data' > 'Filter' > 'Reset Filter'

  

This worked with Libreoffice 4.2.5.2 The help page for 'Standard Filter' is here.

In order to find duplicate rows and their respective counts on MS Excel or LibreOffice you can use following formula:

=COUNTIF(A:A, "=" & A2)

It will provide count of duplicate records in the cell formula is applied on.

Explanation of formula:

1. A:A is the range in which duplicate comparison will execute.
2. "=" is the operator to compare records for duplicacy.
3. & A2 is the value which will be compared in the range i.e; A:A (Column A)

You can use filter to check duplicate records with X no. of duplicacy.

Check screenshot for application of this formula: