Wouldn't Kabuto->Kabuto-orochimaru be more like a Yamato? Kabuto is a compatible host for Orochimaru's DNA. One's soul isn't in their DNA, identical twins don't have identical souls or even personalities and disease susceptibility. Now there have been bizarre instances where identical twins, as noted by Jung, did amazingly similar things in their life like marry women who looked the same, get the same job, name the son the same name. This combination of DNA and host could serve to make a character similar in personality, but who knows in the world of Naruto. I also don't know if the seal will weaken with time.
I like the theory though, it's fresh.