Hmmm... This was on wafflepool. I will have to try a LTC only pool.
Well, ran 5 overnight on Wafflepool @ 900, and did not notice any difference.
Ran 5 all day on an LTC pool @ 900, and did not notice any difference (all same worker address).
I am running all 10 overnight on an LTC pool @ 900 with unique worker for each. That might stabilize the difficulty. If that helps, then I might retry 5.