If I have two separate businesses as an independent contractor, how do I enter two different schedule C forms?

Will the income and expenses for both businesses be combined into one schedule C form?

No, you will have two schedule C forms but will combine on the 1040 as one income or loss.  

If you have already entered a business, simply add another one in the program by following these steps:

In TurboTax Home&Business desktop edition,

• Open your tax file, 
• At the right upper corner, in the search box, type in schedule c and Enter
• On the screen, Here's the business info we so far, select Add Another Business
• Follow on-screen step-by-step instructions to create a Form 1099-MISC