I see what you mean about 80+99 not totaling 112, lol. I've noticed that when I do a custom study session, if I have any cards that are still in "learning" mode, they'll get redesignated as "new." So you had 6 "learning" cards due today according to your first screenshot, but maybe you have other "learning" cards due tomorrow or at a later date, and those "learning" cards are getting redesignated as "new" cards in your deck. Still, I don't think this is the problem, because you say that you're seeing the same cards multiple times. If my original guess was the real problem, you wouldn't be seeing duplicates. I'm assuming you're not seeing them over and over again due to your own rating of the cards, but it just doesn't add up.
0) Under options, what's your max new cards per day set to? Maybe there are more new cards than you think because you have it set to a deceptively low number.
1) Can you poke around in the Browser view for that custom deck and see how many cards it thinks are in the deck? The number in the deck should display at the top of the window, like this:
View attachment 186693
2) Maybe you've tried this, but I suggest running the check for duplicates command by going to the browser window menu, Edit -> Find Duplicates.
3) Again in the browser, search for Genetics cards that are in learning mode. You can do this by searching for this:
View attachment 186692
If there are way more than 6 results for that search, maybe that's why cards are being listed as "new" in excess of the 112 you expected.
Edit: If you could also include a screenshot of the deck options you have selected, that might be useful info.