Ceropegia candelabrum var. biflora is a synonym for Ceropegia candelabrum subsp. tuberosa.
Ceropegia candelabrum subsp. tuberosa is not currently in the database, but it apparently should be.
The question of whether it is "one plant or two" is hard to answer because it implies a dichotomy that doesn't exist. There is one species, Ceropegia candelabrum, which itself is composed of two subspecies Ceropegia candelabrum subsp. tuberosa and Ceropegia candelabrum subsp. candelabrum.
Or, at least that is the current thinking of the taxonomists who are experts on Ceropegias.
