The scythe was created by Minnie while under Mimi's influence.
Jr grab the scythe that Minnie dropped and attack Him with it.
And then Him get his hand on the scythe.
Conclusion, this is not Jr's scythe, but Minnie's. And since Minnie is currently a free floating soul (aka DEAD), the chance that it is a genuine reaper scythe are close to none.
Hell, did Minnie even have ANY reaper power to begin with ?