YES

1 decompositions
 #0 -----------
   1: f(g(x)) -> f(h(x,x))
   2: g(a()) -> g(g(a()))
   3: h(a(),a()) -> g(g(a()))

@Parallel Closedness
--- R
   1: f(g(x)) -> f(h(x,x))
   2: g(a()) -> g(g(a()))
   3: h(a(),a()) -> g(g(a()))

--- S
   1: f(g(x)) -> f(h(x,x))
   2: g(a()) -> g(g(a()))
   3: h(a(),a()) -> g(g(a()))