This name is a synonym of Cypripedium parviflorum var. pubescens (Willd.) O.W.Knight.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 23512068).
This name record (from Tropicos) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Cypripedium calceolus in version 1 of The Plant List.