In my experience, Musa cheesmani and Musa nagensium 'Florale Noir' look very similar with dark coloured stem at their bottom and a dark leave mid-rib, but musa nagensium 'pure' (mine is still small) has more 'bluish' leaves and until now no dark mid-rib
M. nagensium 'Florale Noir' (Sunshine seeds)
M. cheesmani (Sementes.de)
M nagensium 'pure'? (Tropengarden.de)