I'm just reporting this; I already found the problem. Immediately after upgrading from 9.101 to 9.600, I began getting my daily "audit digest" emails twice. I checked the scheduled tasks, and for both "Resource Audit Digest" and "User Audit Digest," "All Administrators" was checked off in the Notification section. It wasn't that way before the upgrade, as I am the only one supposed to get the reports.