Multiple H-1 approvals

ANSWER

I am on H4 in the USA , I have applied two H1B's through two different employers (Company-A and Company-B) on Apr 1st , 2008 and both have got approved which will be effective from Oct1st , 2008.
I have the following questions

Qo1. Now I have two new I-94's through two different employers ( Company-A and Compnay-B ) plus I have my own H4 I-94 with me. Do I need to return all three I-94's if I leave the US
Ans1. Yes. I usually recommend that all I-94’s be surrendered.

Qo2. As I have two approved H1B's with company-A and company-B, Can I easily switch from Company-A to Company-B later time then to company-A , etc . For this do I need to inform USCIS. Is there any negative consequences in that ?
Ans2. The law in this area is unsettled and unsettling. Not only is CIS inconsistent in its signals, USDOL has its own take on this situation. Bottom line advice – pick one company and stick with it.
As per CIS regs, theoretically, you can have multiple H-1 approvals and all of them stay valid unless withdrawn or revoked. But there are DOL regulations that point in other direction. In appropriate cases, I may advise otherwise, but in this case, you better off picking one.

Qo3. Can I apply SSN now using Company-A H1's approval then join in company-B from Oct 1st, 2008
Ans3. I know of no law that says you cannot do this. So, I think you can.

Nonimmigrant Visas