Okay, try this. It took me a few minutes to recreate the problem on my computer but here's what I think the problem is. Goto your Edit Nurbs menu and goto the Insert Isoparm Options Box. When the options box opens up, look for the "Multiplicity" field. Set it to "1". Then click "Apply", then click "Close". You should have no more problems after that. From your image that you posted, it looks like this field is set to "3" which is why you see 3 CV's instead of one.

Let me know if that fixes you problem, thanks.