You have asked several complex legal questions that may depend upon a variety of other issues and circumstances. If the contract has your signature on it, you can be bound to comply unless you have rescinded that offer before it is accepted.
The same company can have many DBAs. You would need to provide more information to advise if you are bound to duplicate contracts with the same company.
I urge you to discuss this entire matter with an attorney, who can review the contracts and the circumstances.
Call my office for further advice.
Robert J. Spitz
909 395 0909