Strange duplicate files in Advan Monthly Patterns download

Hello,

I noticed that when downloading Advan Monthly Patterns data from the API, some of the files are duplicates so when I'm downloading it will skip exists even though I'm downloading for the first time to an empty directory. So for example, in a recent download of 2019 data, it found information for 39 files but only 35 were downloaded. I'm not sure if they actually are duplicates and it's just a database error or if I'm missing data now.