a bit more explicit

89.md

@@ -74,6 +74,19 @@ Using a `k` tag(s) (instead of having the kind of the `d` tag) provides:
 
 Multiple tags might be registered by the app, following NIP-19 nomenclature as the second value of the array.
 
+No contradictory hints can appear. Apps should not publish handlers with the same `platform:type` duple.
+
+For example: an event with:
+
+```jsonc
+["web", "https://.../path1/<bech32>", "nevent"],
+["web", "https://.../path2/<bech32>", "nevent"],
+```
+
+where the `web` + `nevent` duple is duplicated with contradictory values is invalid and clients SHOULD ignore it.
+
+Applications that have different URLs should use different `kind:31990` to announce the different URLs that should be used per kind.
+
 A tag without a second value in the array SHOULD be considered a generic handler for any NIP-19 entity that is not handled by a different tag.
 
 # Client tag