When we copy DM HTML to the clipboard we mark the first child as not having a valid rendering, so when it is pasted to another VE instance the rendering is recomputed, and we mark the rendering we do provide as ignorable (because we don't trust it not to get screwed by the browser). One or both of these are skipped if the converter is using originalDomElements, so unmodified templates from Parsoid don't copy very well.