Line Item APIs buggy

I am trying to copy line values from one item record to another. In the destination record which is client-side (UI), I load the source item record.

I want to load two lists (vendor and site category lists). It seems when I perform a loop, the first list will work correctly but oddly the second list the indexing is off and nothing seems to work correctly. Here's the code (shortened to only the problem areas).

 var src_recd = nlapiLoadRecord('inventoryitem',xx);  var lists = ['itemvendor','sitecategory'];  // loop through the lists and if there are any contents in the current UI record, remove those line items first  for(var i=0; i<lists.length; i++) {    var cnt = nlapiGetLineItemCount(lists[i]);    if ( cnt > 0 ) {      // remove the items from the list      for(var line=cnt; line>0; line--) {        nlapiSelectLineItem(lists[i],line);        // if list is the first list, the current index show correct.        // if list is second or more, the current index for the first loop shows the        // next index of the previous list that just looped through        alert('Current Index: