; let { tys' = substTys tenv tys
; (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys'
; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches,
; let { tys' = substTys tenv tys
; (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys'
; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches,