That's normal. There are multiple of every boss altar usually scattered around the world, and the stones you find will direct you to the nearest one. Eikthyr's mostly spawn near the center of the world, which can even see you getting some ridiculously close together, like this little spot (there is one on the left side behind me, and one a bit further back on the right, right next to each other):
https://steamcommunity.com/sharedfiles/filedetails/?id=2932255242