Amendment I 797 has earlier H1B expiry date than Fresh petition I797. what will be stamping expiry date?

My fresh H1B petition I 797 expiry date is Jul 2018. My employer filed an amendment due to change of location. Accoring to the I797 in amendment approval is Feb 2017. Im going for stamping tomorrow. what will be my visa expiry date in the stamping?

It will be till Feb 2017 only. Same happened with me. I came across couple of cases in Feb-March where they given visa for 1 year only. My earlier i797 was valid till Dec 2018 and when I switched to new employer new validity is only till Mar 2017. Not sure why.