Why doesn't Erlang's Dialyzer detect difference in state?

Question

I run Dialyzer on the following MVR piece of code which passes the test_function except for the IncorrectMap. Why is that the case when I deliberately return different PlayersMapNew for the case branches although they are specified to be the same. And how can I force Dialyzer to be more strict about my code, such that States are easier to manage keep track of.

My concern especially is if I have filled out the way of making a map type checking correctly , in order to make sure that it is Done in accordance with the documentation. The latter I think is a bit scarce. Can one actually check down to the individual key of a map , whether it is correct or not?

-module(example_module).

-export([my_function/1, state_changer/3, test_function/0]).

-type map_arg() :: #{key1 => integer(), key2 => atom()}.
-type move() :: rock | paper | scissor.
-type playersmap() :: #{players => {pid(), pid()}} | #{players => {pid(), pid()}, fst_mover => {{pid(),_}, move()}}.


-spec my_function(Map_arg :: map_arg()) -> ok.

my_function(Map) ->
    ok.

test_function() ->
    CorrectMap = #{key1 => 1, key2 => 'value'},
    IncorrectMap = #{key1 => 1, key2 => 2},
    my_function(CorrectMap),
    my_function(IncorrectMap),
    state_changer({move, rock}, {self(), tag}, #{players  => {self(), self()}, fst_mover => {{self(), tag}, scissor}}).


-spec state_changer({move, Choice :: move()}, From :: {pid(), _}, PlayersMap :: playersmap()) -> {reply, playersmap()}.
state_changer({move, Choice}, From, PlayersMap) ->        
    {CurId, _} = From,    
    {P1Id, P2Id} = maps:get(players, PlayersMap),
    case CurId of
        P1Id ->                        
            PlayersMapNew = maps:put(fst_mover, {From, Choice}, PlayersMap),                    
            {reply, PlayersMapNew};
        P2Id -> 
            PlayersMapNew = maps:put(fst_mover, {Choice, From}, PlayersMap),                    
            {reply, PlayersMapNew}
    end.