Employer A Sponsor H1b, Transfer to B, still eligible to work for A ?

Situation is like this:

Employer A Sponsor H1b reputated big MNC, petition got approved visa not yet stamped as client postponed requirement in project. hence waiting…

Transfer to Employer B small desi consultant hydrabad based, petition approved.

now my question is after employer B petition approvel does Employer A petition approval notice still valid ??

can we proceed for stamping for Employer A considering client open’s the requirement and preferred to work for A rather then B.

A’s petition would be valid until its expiration date. So you can go for stamping through A as long as they support your employment and visa interview appearance.