Leme ask you Hatcher hens and roos are double yolks viable I been gettin quite a few since mine went back to laying
I would not incubate a double yolker
There aint enough space in there for them to both develop and not enough nutrients either
IF it hatches it will have to be assisted
One will probably die, if not both
There have been cases where it turned out but I would guess thats pretty slim.