If you get a zygote that's a clone, it will be mostly the same apart from mutations that arose in the germ cells in the parent. When you're copying a whole genome, there will always be mistakes. I can't speak for how similar they are to the parent typically, but there can be variation in several nucellar embryos from the same parent. IE, the clones will all differ slightly.
I am finding quit a few regrown fruiting Citrus rootstock plants around here, mainly Citrange, Swingle and Rough Lemon.
I think I can fairly assume that the rootstock seed all came from the one approved source in Australia.
Out of these types, I am not seeing 100 % identical fruit on the trees of any one variety.
These three are highly clonal types, suitable for uniform rootstocks.
It is unlikely that only off types are the lucky ones to survive and fruit.
( on the other hand there may be compatibility issues with off types causing graft failure, but that seems a long shot ).
I am not seeing any major differences in foliage on these trees. You can clearly tell that they are Swingle, or Carrizo Citrange or Rough Lemon.