This name is a synonym of Rhododendron sanguineum var. didymoides Tagg & Forrest.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50060564) with original publication details: Sp. Rhodod. 545 1930.
This name was in version 1 of The Plant List, record tro-50060564, and has not been changed.