In one of FE's theories it is stated that in the space scene when Rinoa is being possesed by Ultimecia and starts going all "multi imaged" one of them looks more like Ellone than Rinoa, even having her acsessories.

However, this may be in the eye of the beheader. I can't remember if I noticed it before, but I can sort of see his point. This a chance that Ellone and Rinoa have similar graphic designs, and the fact that not all Rinoa's fetures are visable in the "images" may simply make one of them appear more Ellone like. It could have been Square's intention though. You never really know until they say.