I discovered a games database called KingBase that's been around for a while that is pretty good. I am too lazy to keep my database which came with Fritz 12 updated on a regular basis, so the games only went to 2002. KingBase has over 1.8 million modern games from 1990 to 2016 in pgn, SCID or cbv format. All players are rated over 2000 Elo. The author claims there are no duplicate games which he has collected from the websites of various tournaments and TWIC archives. There are no games under 6 moves. There is also a Lite version which consists of games from 2000 to 2016.
The games are split up into 15 categories by ECO opening classification so I took the time to copy and paste them into my existing Fritz database. The whole process of copying each group and pasting them into the cbh file took about 45-60 minutes per group because my Fritz 12 program had to convert the theme's, ending classifications, etc. and in the end the DB had 3,119,689 games. I suppose that because there is an overlap of years from 1990 to 2002 there will be some duplicate games, but to be honest, I really didn't feel the need to try and weed out the duplicates. I realized too late that I should have downloaded the Lite version which would have avoided most of the problem. After that task was completed I made a new opening book from all 3 million plus games to 30 plies (15 moves) which when finished gave a book with 24,347,594 positions. With the duplicates that means the opening statistics will be somewhat skewed, but for me that is not a big problem. The book should be sufficient for my purposes.
If you are looking for a good database of games to download KingBase is an excellent source.