H1-b Transfer, want to go back to company A

[adisunshine]

Hi All,
I am in a real dilemma. I was working with Company A, which is a consulting firm. My project at client end got over and company A did not have anything in hand.

I got an offer from Company B, took H1 transfer for Company A's visa and started working with them. I did not tell all this to Company A.

Now Company A came back to me and said that they had another project for me. I want to join back Company A as they are in the middle of processing my green card.

Can I go back to company A now? They do not know that I am working with Company B. What are the legal rules and restrictions on this? Will my green card processing be hampered in any way. But the most important question is that can I go back to working with Company A despite taking a transfer on their visa?

I have to start on the project for Company A from Apr 1 and will really appreciate replies from you gurus.

Thanks,
Adi