How does the sum operation work betweem 2 operators?

[Veenty]

I have a complicated code and its kinda mysterious where things really go wrong. So some guide on how the operation sum works would be great.

My code kinda goes like this

function mul_custom!( b, SpecialStruct, x, alpha, beta    )
#do stuff

end


N = 20
SS = SpecialStruct()

G =  LinearOperator(Float64, N, N, false, false,
                        (res, w, α, β) -> mul!(res, SS, w, α, β), 
                                    nothing,       
                                    nothing) 

So here is where stuff goes weird

v = rand(20)
Op1 = OpEye(N,N) +G
Op2 = G +OpEye(N,N)

res1 = Op1*v
res2 = Op2*v
res3 =OpEye(N,N)*v +G*v

res1 = res2 #false

res2 = res3 #true

There probably is a weird memory usage on my custom mul!, but I do not know how to even begin looking for the error given that the applications by its own do work