Photos Library duplicate??

Hey all! I was cleaning out some files on my Mac today when I stumbled upon a "Photos library" type file. I clicked on it and it opened Photos, but it only had about half my photos!! After some investigation, I found the *other, original* "Photos library" file in my system that had my entire library. This concerned me a lot. I have two libraries: 1. user/Library/Photos/Libraries/Syndication.photoslibrary 2. user/Pictures/Photos Library.photoslibrary Is this normal? If I delete that alternate "Photos library" file, is that fine? Where "should" my photos be stored -- aka, which one is the default one? Thanks!