Update: Walmart confirms that duplicate orders for the SNES Classic are being cancelled. Here's the statement:
Customers who recently pre-ordered the SNES Classic from Walmart.com will receive the console after it launches later this month. Because we want to make sure as many customers as possible have the chance to purchase this highly-sought after item, there is a one unit per customer limit on SNES pre-orders. We did experience a temporary issue which allowed more than one item per customer to be ordered. We emailed customers who ordered multiple units to let them know we plan to ship them one SNES Classic and that we’ve canceled the extra units they ordered.
SNES Classic Edition pre-orders have not been without drama. Launch day was a mess, with most units selling out near-instantly and multiple sites experiencing technical trouble from the crush of eager customers. And the drama is not over, apparently: Walmart may now have begun to cancel some of those pre-orders after the fact, though it's not as bad as it sounds. According to NeoGAF and Reddit, the retailer is cancelling duplicate orders only, and it appears that only the additional orders have been cancelled. We've reached out to Walmart for confirmation and will update with any new information.
It seems like this is meant to offer some relief for the rash of bot-assisted resellers that appeared to snatch up all available inventory when the consoles were made available. Resellers knew that the SNES Classic, like the NES Classic before it, would be a hot item this holiday season. That, combined with the relatively low MSRP of $79.99, made snatching a ton of orders and putting them up on eBay for $200+ a pretty sound businesses decision. While it's impossible to tell just how many units went to genuine customers and how many went to scalpers, what we can observe suggests that this is a major problem for Nintendo's "Classic" line.
It's worth noting that back in July Walmart made some pre-orders available before it was supposed to and cancelled those as well. These two instances are similar only on a superficial level, of course.
While this move may primarily be intended to affect scalpers, there are likely some people who placed multiple orders legitimately: ordering an extra console for a friend, or as a present. Still, it would seem like the right move under the circumstances. Bots were a huge problem for launch, and I can support any effort made to ensure that consoles make their way into the hands of actual people that want it. Scalpers will continue to be a problem unless Nintendo increases supply or price, but I don't see either of those things happening in a meaningful way.