Historian logging more than it should for on change

I was doing some scripting with the tag historian functions and noticed something unexpected in a result so I queried the actual historian table and found that a tag I have set to log on change seems to be logging more frequently, here is the result of my query -

Any ideas why I would see this? These are the history settings for the tag -

You're not using storeTagHistory anywhere?

No it should not be.