chisel Vec() in Bundle class cannot be implemented in Module class

The chisel version I'm using is 3.2.2. When I try to create a Vec of member in a Bundle class, code is like,

class myIOBundle extends GenericParameterizedBundle {
  val en = Vec(4, Output(Bool()))
  val aa = Input(Vec(4, Bool()))  // Used in Debug.scala of rocket-chip
}

then I implement this Bundle class and pass it to IO of a Module class, the code is like,

class myModuleClass extends Module{
  val io = IO(new myIOBundle)
  ...
}

Then I got the error says :

[error] chisel3.package$RebindingException: Attempted reassignment of binding to UInt<3>(4)

But I see the same use of Vec in Debug.scala of rocket code. Is this error encoutered in old chisel version, not the chisel 3.4.3, since the rocket is using chisel 3.4.3?