Assignment/Object Creation fails for non-@ref/@ref:external properties when reusing a value object previously assigned to an @ref/@ref:external property.

## Summary
Assignment (and/or object creation) fails for properties without `@ref` / `@ref:external` metadata when the same value object instance was previously assigned to a different property that is decorated with `@ref` or `@ref:external`.

## Observed Behaviour
When a value object V is first assigned to a “tagged” property (e.g., propTagged annotated with `@ref` or `@ref:external`), subsequent attempts to assign that same object V to an “untagged” property (e.g., propPlain with no `@ref`/`@ref:external`) fail.

This can happen during:
- direct property assignment, and/or
- object construction / deserialization where the same value object is reused across properties.

## Expected Behavior
Reusing the same value object instance across different properties should not cause assignment/creation to fail solely due to metadata differences between the properties. If V is valid for propPlain by type/shape, it should assign successfully regardless of whether it was previously used with a `@ref` / `@ref:external` tagged property.

## Workaround
- Cloning/copying the value object before assigning to the untagged property.

ファイル、テスト、エントリポイントは特定されていません。まず、タグのないプロパティ上で、@ref または @ref:external プロパティから1つの値オブジェクトを再利用するケースを再現し、直接代入と構築またはデシリアライズの両方を対象にします。クローンを要求せずに有効な再利用が成功すれば完了です。

索引モデルが issue の本文から書いたものです。