I don't like it, but then I've never liked
Destiny as a name either.
"it's very comic book character to me." - interesting that you get that impression, because from what I've seen most actual comic book characters tend to have very normal names like
Elizabeth,
Katherine, and
Jane. At least for their real names. Dynasty sounds like a superhero name chosen by a teenager trying to sound cool (
Storm, Starfire, Karma, Jubilee, Armor, Polaris, etc). The repeated initial thing is an entirely valid point; it always looks at least a bit silly, even in comics.
Dynasty also feels like an awful lot of pressure put on a child: "You're our legacy; it's up to you to carry on our family, uphold its honour, etc." (I think this is also my main problem with
Destiny, actually.)