model M1

  parameter Real a = 1;

  parameter Real b = 1;

end M1;



model M0

  parameter Real a = 0;

  parameter Real b = 0;

end M0;



model N

  replaceable M0 m;

end N;



model B

  N n(m.a = 3, redeclare M1 m, m.b = 3);

end B;

I simulated model B in OpenModelica revision19412.
it turned out that:
n.m.a = 3
n.m.b = 1

To my understanding the order of modification should not matter, so I guess this is a bug.
I read the Modelica spec chapter 7, about inheritance, modification, and redeclaration and it doesn't mention combined modification and redeclaration specifically, so I guess B should be equivalent to:
model B
  N n(redeclare M1 m(a = 3,b = 3));
end B;