In retrospect it looks like something buggy on Mojang's end. Don't worry too much if it happens. Just hop in stacked end portal :P
If it reaches world height or gets ridiculous I'm sure that SS will do something about it. Something like this is no reason to get upset (only 2 portals stacked on top each other, I mean). If it seriously becomes an issue, something will be done.
Comments on Profile Post by Slvr