Bridge & your devices · Collab Sync
Is Collab Sync a backup?
Short answer: Not on its own. Collab Sync mirrors edits — mistakes included — to the other Mac, though deletes don't carry across by default and conflicting versions are kept. Keep a separate backup for older versions.
Not on its own. Collab Sync keeps two copies in step, so an edit you make — including a mistaken one — is sent to the other Mac too. It does protect you in some ways: deletes don't carry across by default, and when both Macs change a file the other version is kept beside it.
For a true safety net with older versions you can go back to, keep a separate backup as well.