Longshot- Anyone ever have Cisco CUIC reports where daily totals and monthly totals aren't adding up?

Our call center reports are showing different totals for daily vs. monthly reports. My boss says our Customer Service department reports this as an issue every 2-3 years, he opens a ticket with Cisco, and they say there's nothing they can do as the totals are pulled from different databases, or some such thing. Can anybody shine some light on this for me?