I think you need to reference the current item number dynamically by surrounding the parameter with pound signs: #For_Next_Loop_0.CurrentItem#
To do what I think you are trying to do I would probably use the for next with an increment of 2 and then get the two rows with something like Data.Results{/Rowsets/Rowset/Row[#For_Next_Loop_0.CurrentItem#]} to get the first and Data.Results{/Rowsets/Rowset/Row[#For_Next_Loop_0.CurrentItem#+1]} to get the second.
Regards,
Christian