Interesting birds! I've never heard of verified purebreds having red body parts (it's always "Oh, yeah, my red chickens are in the pen over but it's DEFINITELY not a hybrid"), but they are thought to be fairly recently descended from green and red junglefowl, so I suppose that they could have red marks if something goes wrong genetically. There are too many factors to perfectly account for the offspring's phenotype, but it could even be that some of the DNA that formed the bird was damaged or incomplete. Some people get birds like this from reputable breeders, but, again, usually they'll have some kind of close-by other breed near their breeding hens. Likely a hybrid. It could even be that a few generations back, the birds crossbred and one of the parent birds carries a red allele. It could be that they tried watering down their flock to make more, or received illegitimate birds themselves. Even birds straight from Indonesia wouldn't be entirely reputable, as they could have other breeds of chicken nearby, or their birds could even be bred by wild chickens in the area. There are so many different circumstances to account for. He's obviously not breeding quality, but he looks like a sweetie! I love the contrast of his red eyes on the black skin around it.