Constraint tuples aren't (always?) normalized

CTuples.hs

 {-# LANGUAGE RankNTypes, ScopedTypeVariables, TypeApplications, ConstraintKinds #-}
 module Main where

 import Data.Constraint
 import Unsafe.Coerce

 newtype MyInt = MyInt Int
 instance Eq MyInt where { _ == _ = True }

 flip' :: forall a b. Dict (Eq a, Eq b) -> a -> a -> Bool
 flip' d x y = case unsafeCoerce d :: Dict (Eq b, Eq a) of
                 Dict -> x == y


 main = print (flip' @Int @MyInt Dict 1 2) -- prints True