Every story has a basis on another.  Nadia was 
inspired by Laputa but it also has aspects taken 
from 20,000 Leagues under the Sea.  I know a few 
folks that work at Disney who have never even 
HEARD of Nadia before and they worked on 
Atlantis.  I mean, how many times have we seen 
the saaaaaaaaaame type of anime come out?  Look 
at any genre of film and you're going to find 
ones that have very similar aspects.  I'm not 
debating on Kimba VS Simba, that's sorta a dead 
giveaway HOWEVER, Kimba and Simba's plot is a 
very old one.  LOOK AT SHAKESPEAR'S MacBeth fer 
cripes sake ;P

How many boy meets girl, boy falls in love with 
girl, boy loses girl to other man, boy fights 
other man to get girl back, boy must overcome 
some mental obstacle to get girl back.  Boy wins 
girl back and Happily Ever After have we seen?  
It's a very basic recipe.  ;P