Time-series collections do not enforce measurement-level_id field uniqueness. However, if the _id field values of two or more measurements in a time-series collection are ObjectId types and coincide, there's a decent chance that the values coincide because of an issue with the server inserting duplicate data as opposed to clients issuing insert commands with measurements with the same _id field. This would help with making issues like SERVER-131302 detectable.

This ticket would involve adding the ability to detect this as part of the validate command, either as a warning or error.