Duplicate Serial Numbers

It could be that he used a stock photo instead of actually taking a picture of his speakers.   Are yours the same finish?

So what I meant is maybe he used a picture of your speaker he copied from mfg site

Model numbers are not unique, but serial numbers are specific to that item. 
 

It isn't unusual for scammers to find photos off the internet--often from a closed sale transaction years earlier.  I was looking at an amp and had a bit of alarm, call is a mild yellow on my BS meter.  I google searched the photos, found them on an ad on a small audio site that closed 2 years earlier, and confirmed the scammer did not have the amp.  I pretended I wanted to buy it and got far enough to indentify her as a lady with red hair in Nigeria but was unable to do anything across international borders.  Use google photo search to see if the photos are elsehwere on the internet.  --Jerry

Spoke to the manufacturer. Was advised that the speakers look authentic and that it may simply have been an accidental duplication of serial numbers.

So the manufacturer confirmed that its serial numbers don't guarantee authenticity, because they can potentially duplicated for reason or no reason. 

What brand of speakers? Low end? I assume.

This is the mark of poor manufacturing practices at best. If there are actually two sets on the market which came to light by a random person (no offense to you)… then there are dozens or hundreds on the market. 
 

Actually, they’re pretty high end. But, I won’t disclose the name for a variety of reasons. I have several pair of speakers though, and hope this isn't a prevalent issue in the speaker world.

Both speakers same ser #   or consecutive?    That sure is weird

Same serial number R/L.

Perhaps a printing error?

Could have happened with a breakdown/restart or when adding new paper stock.

DeKay

Sloppy regardless of the reason. What else in their QA process is failing? 

If they're "pretty high end" and they told you they can't keep their serial numbers sequential without duplication, I'd have a hard time believing they'd support or warranty their products if something happened. Major red flag for the brand. 

red flag.

I'd be worried about a manufacturer who can't keep serial numbers straight.  How are they with matching drivers or crossover components?  Can't be good.