rob > I don't know (haven't looked) whether, when you uplist to a senior exchange, if rules prevent having the same symbol as an existing junior ... e.g. V.PET and T.PET being completely different companies?

No, this is not possible. All stock symbols across the Venture and TSX exchanges must be unique. The only way for Poet to get PET, is if Peat changes its stock symbol, or if Poet buys out Peat (not worth it!)