Avoid having multiple primary actions in close proximity with one another.
When there is more than one call-to-action use the primary button for the more
important action and the secondary button for the other one.
Explanation
The image shows a comparison between two UI designs for an extension, where there are more than one call-to-action. The first design has two primary actions in close proximity with one another, which is not recommended. The second design uses a primary button for the more important action and a secondary button for the other one, which is the recommended approach.