I’ve just confirmed and the ID is unique to each environment. For example, you may have the same ID for different items in a given development and a production environment.
If sys.id is unique only within the scope of an environment and not across environments. Can you please confirm conflicts and overwrites during import in the scenario below are possible?
Scenario: Authors like to setup content in Stage environment prior to a feature is meant to go live in Prod. If id1 is of content type A in Stage environment and is being imported into Prod environment which already has another item with id1 but is of content type B, then import would fail due to content and content type schema mismatch? In the worst case if both items are of the same content type but are logically different items, then import of one would overwrite another?