It is very probably one tuber - 2 stems, one of them got tired and died. Nothing wrong with it.

I grow this plant - and in my conditions it is almost indeterminant - grows and blooms on the very ends on long stems - and keeps growing. Eventually they got so unsightly - I chopped them off - and put the tuber to rest - 2 months later - it sent new shoots - and I potted it again. When I cut the long stems off - I rooted the tips - it roots easily under the dome - and passed them to my gesneriad club friends.

So - it is your call- to let it be - or to chop the remaining stem and let it rest. Sometimes the old stem is still growing - and the tuber sends a new young stem. In this case I would chop the old stem - and let the new one grow, And do not forget to put the tip for rooting - it is a very desirable plant - so you can share it.

Irina