Harold said it perfectly.
Het mean heterozygous. So a pastel is the heterozygous form of the Super Pastel. Just like a lesser could be named het BEL.
Het Red Axanthic, have a black back. And the super form is the red axanthic.
Corey Woods have it clear on his website : http://www.coreywoods.com/het.shtml
But I just don't understand why say you have 2 pastel possible het ? You either know if it's one or not. I don't think many produced pastel het red and your pastel have either a black back or not. They can't be "possible". You might have been fooled when you bought them unless they come from Corey Woods or someone else who produced them (not many yet I think).
May be Corey Woods will come and clear it up for you. Otherwise you can try to get in touch with him (don't try email, he is bad with it
)
btw : Here is a link to his Pastel Het Red from 2005
http://www.coreywoods.com/PhRA.shtml
But to me, it looks soo tiny that it could be a problem in the egg development. And not because it's a black back that it's a het red
There is other black back that don't have a super form out there.
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love this world, don't hate it.