42 coin is 47.9395 diff. and half of dogecoin is coming from middlecoin which means that it represents 200 diff. Nice try.
Doge coin has a rate of about 25 GH/s, and middlecoin doesn't mine it continuously. So, middlecoin is probably about 1/3 of doge.
42coin fluctuates in diff quite a lot, due to its very short difficulty adjustment, but has been averaging about 60. Also don't forget that block times are differernt, so difficulty isn't directly comparable and must be converted. Difficulty of 60 in doge is equivalent to difficulty of 42 in 42.
In short, 42coin has been averaging a hash rate of about 6-10 GH/s. Middlecoin would make a big dent to the profitability, but it wouldn't crash it.