The number of nonces needs to be a multiplier of the stagger. 800000 isn't of 8192. The program fixed it for you, but you didn't notice it the second time around.
Delete the second plot file and make this: 14763352218983602599_802816_802816_16384.
More information about overlapping can be found here: https://forums.burst-team.us/topic/288/plots-101/5