Hi
Usually for all DLP object (policy, report, account, role, attributes,...) number between parenthesis are just ID of the object. This ID is used as object key in DB and for all URL in enforce UI, so like that (for example) you are able to change object name with out any issue.
If you connect to enforce UI and just put your mouse cursor on your policy name (withotu clicking on it) and check hyperlink name you should see a policyID=121.
So in policy log, i think it is just a mistake to dont put it always (or put it once depending on the right version). But it is the same policy.
Regards.