Can you post a screenshot of what you are seeing? I'm not sure I understand exactly what you mean, but you should be able to view any underlying data in your workbook, I believe.
I have done a data blending on 2 data sources(one is a primary data source and other is secondary) and in underlying data i am able to see only primary data source but not secodnary.
I understand that--but I don't know where you are looking, and Tableau is a very visual program. A text description is difficult to troubleshoot, at least for me. You should be able to see the underlying data in both sources, or at least I can in my workbooks.
Matthew, he is probably using the "View Data" context menu item or button (on the tooltip).
We don't show "blended" datasets together in the same data window, in any case. Sorry, Yashwanth. I did a little experiment, and even if I added a calculated field in DS1 which referenced a field in DS2, the field in question still didn't show up in the "View Data" dialog for DS1.
Yashwanth, you best bet is probably to create a small-ish text table which includes the mix of fields that you want.