At this point, if the plant you got from Walmart is still small, I would wait on naming it until it is more mature. As with most plants, stems and leaves change as the plant matures and the adult leaves(fronds for ferns, so to speak) are produced. By then you should be able to tell the difference between the two. Also look at the how the frond is divided between the two and the leaf shape. I'm not sure if the spore cases that appear underneath are in different configuration or not, since I've never seen them. This is about as much as I can offer. But until the mature fronds are produced on your rescue plant, I wouldn't make up your mind on naming it.
