Drop enabled, but no updation to the dataprovider in datagrid in Flex

Question

I have two datagrids with data.
dg1 is dragEnabled=true and dragMoveEnabled=true.
dg2 is dropEnabled=true.
When I drag drag items from dg1 to dg2, two changes occur.
1)Item is removed from dg1
2)Item is added to dg2

But I dont need the second thing to happen.
Items from dg1 should be removed and items should NOT be added to dg2.

Can someone give me some idea on how to proceed with this....?