contracts for "overlapping" parametric types

What version of Racket are you using?

6.7
6.10.1
head

What program did you run?

#lang typed/racket/base

(require/typed racket/base
  ((values id)
   (All (A) (-> (Un (Vectorof (Pairof Boolean A))
                    (Vectorof (Pairof String A)))
                Any))))

((inst id Symbol) (make-vector 1 (cons #true 'A)))

What should have happened?

No error

If you got an error message, please include it here.

id: contract violation;
 none of the branches of the or/c matched
  given: '#((#t . A))
  in: the 1st argument of
      (parametric->/c
       (A4)
       (->*
        ((or/c (vectorof ...) (vectorof ...)))
        ()
        (values g10)))
  contract from: (interface for id)

Thoughts

• this should succeed because only one of the 2 or/c clauses could possibly match.
• related to: https://groups.google.com/forum/#!topic/racket-users/xJlDo2KKY2I
• 6.10.1 accidentally fixes this for HashTable by merging the types into a contract for (HashTable (U Boolean String) A). (But #575 reverts that fix.) I guess we could use that "merging" solution but it would better to remove all merging instead of adding more.

Start with the typed/racket/base reproduction in the issue and inspect how require/typed generates contracts for the overlapping parametric vector types. Confirm the behavior across the listed Racket versions and related HashTable case; done means the shown call succeeds without a contract violation while preserving correct contract checking.