Hello, I know this is a really old post but recently ran into the same problem and couldn't find the solution easily. The problem with the slightly different tiles after the split scanline renders were done was being caused by the cache calculated on each tile, pre-calculating the cache and using the load-from-file option was the solution in my case. Hope this helps someone with similar issues!
By the way, this was an amazing render for 2018! It stands tall even today, excellent work as usual Jeff.
Cheers!
