Distribute with reference data create additional rows

Hi,

I have a layout for a single employee. In the lead columns I have 2 characteristics relating to the employee and the 12 posting periods, and in the data columns I have the key figure. I am trying to 'distribute with reference' using the previous year as the reference. It works ok if the the lead columns are the same as the previous year. However, if the lead columns contain different values to the previous year, new rows are created when I execute the distribute function which is incorrect for my purposes. Can anyone advise?

Regards,

Linda