Military Classified Scene IDs (Studio Codes)

Howdy!
When preparing some MC scenes for metadata uploading to Stash, I realized that the scene IDs (studio codes) that are shown at the start of each video (MC + a number) can be shared by several videos featuring the same performer (so I think they are sort of used to indicate a shooting day rather than individual scenes). OTOH, the relevant pages on the website feature scene IDs that refer to the performer’s name (e.g., TJ) and a sequential number—so, e.g., tj4. When uploading my metadata, I—after being corrected in my first MC scene metadata upload—have been using the MC format for scene IDs; but recently, I came across a scene in the DB that had the other ID format (e.g., StashDB).
So, I guess the question is: Which ID format should we use? The “MC + number” one, which sometimes identifies a group of scenes rather than a specific scene? Or the “Performer’s Name + number” one, which identifies each scene on the website?

ETA: For information’s sake, when a scene is scraped from the website, the latter type of the studio code (tj4) is downloaded automatically.