[1 of 1] Processing p
  [1 of 1] Compiling ShouldFail[sig]  ( p/ShouldFail.hsig, nothing )

bkpfail18.bkp:3:18: error:
    Duplicate instance declarations:
      instance Show Int -- Defined at bkpfail18.bkp:3:18
      instance Show Int -- Defined in ‘GHC.Show’

bkpfail18.bkp:4:18: error:
    Duplicate instance declarations:
      instance Show Int -- Defined at bkpfail18.bkp:4:18
      instance Show Int -- Defined in ‘GHC.Show’