Consequences of incorrect VersionedSchema.versionIdentifier

About 4 months ago, I shipped the first version of my app with 4 versioned schemas that, unintentionally, had the same versionIdentifier of 1.2.0 in 2 of them:

V1: 1.0.0 V2: 1.1.0 V3: 1.2.0 V4: 1.2.0

They are ordered correctly in the MigrationPlan, and they are all lightweight.

Migration works, SwiftData doesn't crash on init and I haven't encountered any issues related to this. The app syncs with iCloud.

Questions, preferable for anybody with knowledge of SwiftData internals:

  1. What will break in SwiftData when there are 2 duplicate numbers?
  2. Not that I would expect it to be safe, but does it happen to be safe to ship an update that changes V4's version to 1.3.0, what was originally intended?