I found a bug in gravity tales. At the moment I've only found one fic that's affected, and it was heartbreaking.
http://gravitytales.com/novel/shuras-wrath
Apparently, the story downloads everything twice. I was at the halfway point thinking I had another 750k words to go before I had caught up, only to find out that no... I was caught up, the chapters started again from the beginning.
I cried a little.
Anyway, it's not exactly a major bug or anything, just wanted to report it. If I find any others on gravity tales that do the same thing I'll note it if needed.