Ads-script to duplicate rows in a sheet while iterating

1. When I run an ads-script to call the "spreadsheet" API. I want to enrich a sheet by duplicating some rows according to values I have in a script.

How should I do this effectively?

only by creating a new tab? Starting from the last row? As I change the range while iterating.

  for ( i = 0; i < lastColumn - 1; i++){     for ( j = 0 ; j < lastRow - 1; j++){       var kw_data = kw_to_label[rangeValues[j][i]];         if(kw_data != null){         sheet.getRange(j,i).setValue(kw_data.labels[k]);   

An example:

dict: k1 -> val1, val2 k2 -> val3 

and sheet: