Visa stamping when you have two WAC numbers from same employer

[sk10]

Have question on visa stamping. Came to US on L1.Changed employer who sponsored H1B(valid till May14,2015-for this never got visa stamped)

With same employer got H1B extension with new WAC# valid from May15-2015 to May14-2018.Going to India from Mar7-Apr5,2015.
For visa stamping while filling DS-160 which I797-WAC# needs to be entered?

1.If I enter latest H1-details(valid from May15-2015 to May14,2018),not sure if I will be allowed to enter till May15-2015
2.If I enter old WAC number(valid till May14-2015), not sure if I will get visa stamped till May14-2015 only
3.At Port of Entry what will be the circumstances for above scenarios.How to handle this

Both WAC numbers are from same employer and I-140 is approved Could someone answer my question. It would be of great help.

Thanks