Can we hold multiple H1B at a time?

[amolp]

Dear friends,

I am working for a company "A" with H1B and company B filled H1B transfer and got the approval letter. Now, I decided to accept a company "C" offer and do not want to join company "B". Comany C will file my H1B tansfer in next 15 Days so, can I continue working with company "A" till company C apply for the H1B transfer.

Do I need to complete any formality and can I work for company A for next few days.

Your guidance is really appreciated.

Thanks.