Twins

[boris no no]

i think that edgar is hotter then sabin!! i'll go out with him!!

[Takara]

Identical twin or not, keep in mind that Sabin spent 10 years training while Edgar was sitting on the throne, so of course they would have a different build. Sabin has darker skin and lighter hair, but that might just be because he spent a lot of time outside.

And just because Matron said he looked so much like his father doesn't mean she was talking about his appearance. I always interpreted it as Sabin and his father having similar personalities.