Hi Vikas :
As you can guess from the manual, a mapping load only consider two fields. One is the key and the other the value as you have explained perfectly.
If you need a composite key just create it concatenating both fields in order to create an unique key. For example yo can create Salesgrp & ' .. ' & Hqrd.
Hope that helps.
no you can't do this through applymap
it based on primary key
but for that you can create a field SalesGrp &'-' &HQID as Primary
and use that field and on above side write field there it become easier for matching and if values doesn't match then
the same value it is coming or you make it null also like
ApplyMap ( 'map1', ID, '#N/A' ) It will return matching data with name and else #N/A