Never rely on core strings for translation, they may change or get a context parameter any time. Once that happens your users get a partially translated interface, and your translators have no way to fix that.
Also keep in mind the same string is not necessary translated everywhere with the same word. Even without a context parameter it might be useful to use a different translation for your plugin in some languages. But this wouldn’t be possible if you don’t include the string in your plugin.
See this chat discussion we had some days ago about this topic.