Yes, it appears that you are required to file both a part-year resident Form 502 and a non-resident Form 505.
I'm not aware of a way to file two state returns for the same state within a single TurboTax tax file. Absent a way to do this, I would use the CD/download version of TurboTax, prepare the federal tax return, save two copies of the tax return file at this stage, then prepare the part-year resident Maryland tax return using one copy and prepare the part-year resident California and nonresident Maryland tax returns using the other copy. You'll need to check carefully to see that credit for taxes paid to another state are correctly handled on each of the state tax returns.
(It actually may not matter which file is used to prepare the California tax return, or you could prepare the California tax return before making the copies in which you'll prepare the Maryland tax returns.)
