H1B pay overlap with Indian company

[blackthunder]

I came to US on H1B for company A in may 2009, while working in company B in India. I resigned from company B only in OCT 2009 (6 months later) .During this time I received pay in India from employer B as well as from US employer A . Now I have joined company B's US branch (H1B transferred to company B) and they are ready to process GC.

To avoid problems/confusion , I asked company B in India if they could give me experience letter only till May even though I worked till Oct and (as expected they refused).I am worried that USCIS would flag my case down because of this overlap. My questions:
1. Is it against immigration law for me to get paid salary in India AND in US at the same time?
2. What are the possible problems I may face downstream?
3. Do you have any suggestions on how to cover the overlap period?

Thanks in advance!

[immihelp]

How did you work for company B in India from May 2009 to Oct 2009 if you were in the US working for company A?

[blackthunder]

I was doing support work at night from US for company B in India and got paid in India. I filed income tax as well for the same in India.