If one line of business (DBA number one) happened to be doing poorly, it would adversely affect the fortunes of DBA number two --because, again, its all part of the same company.
It would be best to speak to your accountant--or whomever would be handling your books--to see if your scheme could be handled easily or if it will cause unnecessary headaches (and markedly increased bookkeeping and accounting fees).
Nina L. Kaufman, Esq. is an award-winning New York City attorney, edutainer and author. Under her Ask The Business Lawyer brand, she reaches thousands of entrepreneurs and small business owners with her legal services, professional speaking, information products, and LexAppeal weekly ezine. She also writes the Making It Legal blog.