How to reduce user confusion between my Undo button and Android's Back button?

1. Why did Android Remove Back button?
2. Can there be 2 primary buttons?

Why did Android Remove Back button?

Google acknowledged that gestures don't work for all users. It added that gestures are harder to learn and takes some time to adjust. It also admitted that gestures can interfere with the way people navigate the app. Google also revealed that Android users love the Back button and is used 50% more than the Home button.

Can there be 2 primary buttons?

Primary. Primary buttons are used for actions such as 'Submit', 'Continue', 'Finish', or 'Log in'. They enable the user to complete the most important action on the page. There should only ever be one primary button on a page.