Does storeTagHistory throw out all data if any of it already exists?

I am attempting to read in csv’s and putting the data into historian using storeTagHistory. I’m a little confused about its behavior. Every so often the data doesn’t make it into historian and I can’t figure out why. I’ve added tons of logging to prove that the data is being read in and passed to the function correctly.

As I was reading through the csv’s I noticed that a piece of data (Which is a flow total with a timestamp) is duplicated from one file to the next. So for example…in a csv file it has a data point for 4:00 p.m. and another for 8:00 p.m. In the next csv file it will have a reading for 8:00 p.m. and 12:00 p.m. See how the 8:00 p.m. piece of data is in both csv files?

So my question is in how storeTagHistory behaves when it is fed data that already exists in historian? If it finds duplicate data will it throw out all the other data fed into it? Or will it just skip that one and attempt to insert the next?