If the calendar is embedded in one area of the website, clicking an event brings up a unique website URL (let's refer to this as LINK A).
If you also use the custom domain option and click that same event from the custom domain page, a different link is displayed (LINK B)
Below are the structures of the URLs mentioned above:
If a custom domain is active, then events should only exist in one place on the website. That also brings up the calendar hosted off the time.ly domain. This calendar should also be inaccessible (should search engines discover it) where a calendar owner has deployed a custom domain: