Duplicate 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.