Are you using the Online web version or the Desktop CD/Download program? Yes you can save your return and start another.
How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
For Desktop go up to File-New. It will ask you to save your return. And Be sure to save frequently, go up to File-Save or Save As. Save each return with a name you can tell apart from another one. Especially if another return has the same name or initial. Like a father and son. Or if you have the same name the second return might overwrite the first one.
