I would guess the blue skinned chick is a Colloncas x Huastec cross. I have a number of this same cross myself. The dark skin and beak at hatch is indicative of carrying at least one Fibromelanism (FM) gene. The Colloncas are not Fibromelanotic and so do not carry the FM gene, The FM gene had to come from somewhere. The FM gene is semi-dominant and will show up in first generation crosses. I wouldn't be surprised if that chick and/or some of its siblings turn out crested as well. You can usually tell the crested chicks at several days old if you look carefully. Their down just above the beak tends to be longer, making for a high forehead look and a squarer flat-topped head shape. Some of the Huastec that I received from Yashar were heterozygous for FM and crested or did not have one trait or both. Therefore the second light skinned chick could also be a cross as well. It does look like it may have the high forehead of a crested chick.
I believe I remember Yashar stating that he runs his birds together and then separates them 6 weeks before he starts saving eggs in the spring. I think last year he separated them in February. I would check with Yashar but he may not have had them separated or for that long before he sent the birds to you. There is debate about how much separation time is needed and it varies by breed. I would have thought that 6 weeks was plenty of time, but I have a chick from an egg laid on October 13th that was obviously fathered by a rooster the was sent to freezer camp on July 14th (for being overly aggressive with the hens). That is 12 weeks! That specific chick could only have come from that specific rooster. It was the only SPQ rooster and the only one capable of passing that specific combination of a beard, wide smooth comb (not sure of the name for that type of comb) and non FM. I am glad I took good notes, otherwise I would not have believed it.
As for the rumpless trait. The Collocas x Huastec that I have hatched have ranged from full rumpless to a full range of partial tails. Rumpless is a dominate trait, but there are other genes that can cause partial tails when combined with the rumpless gene. The pure Colloncas should not carry these partial tail genes as these should have been selected out.
I hope this helps explain some of the off-types that some people have experienced, and hopefully help sort out what is a cross or not. You would not want to sell them as pure Colloncas, but they would make excellent free-range birds.
I may be interested in getting some hatching eggs in the future, then. 
