The brick separator is a handy tool to have in your tool box (or in this case brick box). It helps you separate bricks that are stuck together.
Sometimes you will need to have two on hand. As is the case when you have two plates that are stuck together. You just can’t get a handhold on the bottom plate to pull it apart. Especially if the plates are of the exact same size.
Put one separator on the top and one on the bottom like this.
Then squeeze them together until you see a small gap between the plates.
To save your fingernails remove one of the separators and pry the two pieces apart.
Then you have safely separated the two parts without damage to the brick or yourself.