Chestnut Breasted Mannikin Mutation?

[Aussie_Bengo]

Hi All,
The face mask on this left side Chestnut Breast looks quite diluted and "Chestnut" colour rather than the Black of the one on the right. Could it be the start of a Fawn or Isabel Mutation in Australia?
- From a friends aviary in Adelaide, South Australia.

Chestnut, Chestnut Breast_AFF.jpg

[Brooksy]

The overall colour is lighter, the tail & rump isn't as yellow and the head isn't as silver as the other one

[finchbreeder]

Cinnamon or fawn? Any idea where it came from, genetically speaking. e.g. parents? Any idea what sex it is? If I was your friend I would try giving the parents their own small avairy, and observe offspring from them. As well as doing the same with this bird and it's siblings, each one gets a small avairy and a mate, then cousins back to each other. Takes space is the problem of course. But can put them accross avairys with other non Lonchuras.
LML