Can I have more than one WABA accounts under same FB BM ID with different BSP?

Yes, you can. One FB BM ID can make several different WABA accounts in different BSP's. For example you make WABA in company X and WABA in Qiscus. But to create a new WABA accounts you have to submit different phone number with phone number in previous WABA accounts, because one server only have one number and vice versa.