Since you are self-employed as a rideshare driver, you would report all of your income and expenses on a single Schedule C even though you are a contractor for two rideshare companies.
This way, you will enter the total amount of business miles on the single Schedule C since you used the same vehicle driving for both services. This would include the 9000 miles driven for Uber and the 6000 miles driven for Lyft. You would also enter your personal miles as well. You would not need to report the miles driven for each one separately on your tax return since the same vehicle was used.