Visa with employer A, Travel with Employer B petition

I got petition filed with Employer A and B as cap exempt and consular processing. both petitions got approved.
Got visa for employer A. But now position is closed with employer ‘A’, because of some delay. Not traveled with the employer ‘A’ visa.
Can i travel to US on employer ‘A’ visa, showing employer ‘B’ I-797 at port of entry(immigration check or immigration officer) and work for employer ‘B’?
Or do i need to go for visa stamping for employer ‘B’ to travel to US for employer B?

It is ok to travel on B’s petition and A’s visa stamp. It is not required to get visa stamp in B’s name.