Is this egg a twin?

[tanithcrane]

I didn't notice it till tonight but when candling this egg it looked like there was two separate embryos and they were moving separately on the pictures it's not clear and looks like one chick but I couldn't get a good photo as they were moving around too much, it could be just the head and feet but somehow it's looks different to the others I've hatched in the past
If it is just one chick please tell me I've never hatched twins before

 

[tanithcrane]

Sorry forgot to say the embryo is 13 days old

 

[MysteryChicken]

I see only one embryo.