Actually, she has both spangle and opaline feathers.
Opaline and spangle are two mutations, which, if both present, are incompletely dominant to each other, producing a bird that looks like this (as you know):
(Credit to Google Images)
However, it seems that here there was in error in the way that the genes mixed, which made them co-dominant rather than incompletely dominant.
In this case, she shows both spangle and opaline traits separately rather than the usual combined traits. It's definitely very, very unique and I would say probably extremely rare.
This is an example of a spontaneous mutation, which happens naturally as a result of errors in transcription/translation of the DNA.
She's a very beautiful and unique girl!