Yes this is because of the key fields, where in case the key fields are request and data package.
So when you load the same records for second the it considers as a new line
So you should load data from Purchasing item level data to one DSO and top of Purchasing item data DSO >> create a container DSO
after that above load And you can directly load from 2LIS_02_SGR to containder DSO.
Make sure that key fields for container DSO is Purchase order, PO item.
Thx,
Siva