EZY are not far behind, adding new units, and routes, at MAN in 2016 in far greater extent than LPL, but at least they seem not to be directly transferring routes from LPL.
I think if you looked over a longer period, ie 3 or 4 years, you'd see that EZY are by far the bigger offender of expanding one airport at the other's expense. This has been the case at a number of places and LPL v MAN is no different.
Go back to around 2011/12, EZY had 10 a/c at LPL and about 6 or 7 in MAN. FR had I think 8 at LPL but nothing in MAN. Jump forward to 2015/6 and what a difference! Overall, EZY are not much bigger than they were 3 or 4 years ago.
The fact FR are transferring routes directly from one airport to the other if anything shows more commitment to making their routes work.