I have doubts regarding the purity of these animals and several other supposed "Cape Eland' I've seen throughout the gallery, pure cape eland should have no stripes whatsoever. The amount of stripes point toward these being hybrids.
An interesting method of identifying Eland subspecies from the Burger Cilliers's Mammal Guide to Southern Africa:
No Stripes - T.o oryx
6-7 Stripes - T.o livingstonii
1-3 Stripes - T.o oryx x livinstonii
@Nix Being completely honest with you, I think you are onto something and that many of the Cape elands listed in European zoos within zootierliste are listed as that because french zoos tend to write their common name as "Eland du Cap"