Potential A11y Violation:
Multiple main landmark elements exist 
Point of Failure 
A document should not have more than one main landmark.
Available Automation Evaluation 
In checking known available linting and testing tools, these are our findings.
Linting Cannot Exist 
It does not seem possible to have an automated test for this potential failure, yet. We would need a way to identify that a specific template was a "page" template, and that it was the primary page template for the site.
Testing Exists 
See the axe-core library for the landmark-no-duplicate-main rule.
Other Test Methods 
In addition to automated tests, there are other types of tests that could be conducted to prevent this potential violation.
Developer Authored Test Could Exist 
Developers should make sure that their code does not violate this rule, and try to write a test that would prevent a regression in accessibility if the code is later changed.
Manual Test Exists 
Review page and ensure the point of failure does not exist, inspecting the DOM where required.