READ CAREFULLY FOLLOWING THE ***

I model in "Rhino" so Nurb modelling is practicall ALL I know about...

During a loft, you take one curve, then another, and create a surface between the two. A major problem is when you have surfaces which are NOT similar to each other (pentagon lofting with a square) -- it doesn't know which vertex drops where how when.

Though you seem to describe it as an exact copy of itself... in which case there are two possibilities:

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1) When "adjusting seem curves" -- make sure they are all pointing in the SAME DIRECTION. Rhino and Maya may be different, but when you loft -- it creates a curve joining the curves you "loft", and sweeps a surface along the curve it makes.... BUT in all honesty, if you have a square... how do you know where the start and endpoints are... it doesn't, so you need to adjust your "seem curves" accordingly.

To make an example of such...

If you have a wide ribbon coiled around two spools... the traditional way you'd imagine the ribbon to be (in the gap between spools), is in a rectangle shape... but what happens if you turn one of the spools around?

The ribbon in the middle gets twisted out of shape...

When all the "seem curves" are facing uniformly, its like the ribbon is not twisted... when the seem curves are facing oposite ways, its like the spool is twisted...

Mind you it visually will not LOOK like that, necessarily, when you render the glitch... but for troubleshooting purposes... that is an easy way to understand it.

Pros -- feel free to correct me... especially if this is 100% not accurate to Maya and is a Rhino-Only phenominon