No difference to you. Because even your H1 has approved, but you are still in OPT now and WILL changed to H1 (OPT becomes invalid) on 10-1-2004.
You can work for anyone when your OPT is still good. And since you COS has approved and will be in effect on 10-1, you need to 1. work for only Company A after 10-1 (and file for company B later), or 2. company B files another H1 before 10-1 and you work for B when it's approved.
You can work for anyone when your OPT is still good. And since you COS has approved and will be in effect on 10-1, you need to 1. work for only Company A after 10-1 (and file for company B later), or 2. company B files another H1 before 10-1 and you work for B when it's approved.