The Metacrisis was a dumb idea in the first place. Why doesn't the Doctor always just regenerate into their self if that's possible? As an idea it's there for a shock "OMG there's a secret regeneration!" which loses it's power once you realise that no, there really isn't, and to create a second version of the 10th Doctor to give Rose a happy ending, and don't get me started on RTD's weird understanding of happy endings. Lost your dad? Here have a vague copy of him. Lost the man you loved, here, have a vague copy of him. (possibly even worse with Donna- lost your entire personality, have a lottery win- and Jack- grandson dead, have a shag and it'll all seem better)