GHC incorrectly considers type family instances conflicting?

I asked this on stackoverflow first https://stackoverflow.com/questions/44958114/why-these-type-family-instances-conflicting

I'm using GHC-8.0.1. This code (requires singletons lib):

{-# LANGUAGE TypeFamilies            #-}
{-# LANGUAGE TypeOperators           #-}
{-# LANGUAGE TypeInType              #-}

module Bug where

import Data.Kind
import Data.Singletons

type family MkCtx (kx :: Type) (kc :: Type) (c :: kc) (x :: kx) :: Constraint
type instance MkCtx kx (kx ~> Constraint) c x = Apply c x
type instance MkCtx kx (kx -> Constraint) c x = c x

with the message:

Conflicting family instance declarations:
      forall kx (x :: kx) (c :: kx ~> Constraint).
        MkCtx kx (kx ~> Constraint) c x = Apply c x
      forall kx (x :: kx) (c :: kx -> Constraint).
        MkCtx kx (kx -> Constraint) c x = c x

Why GHC considers these instances conflicting? I don't see how they overlap.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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