I have a pair of vortex viper hd 12x50s (2018 edition). The one I originally bought was returned to Vortex under warranty as it wasn't focusing properly. I noticed the replacement had the word "Vortex" on one of the barrels and others that I saw in stores have "Viper HD" on them (see pic attached). Even more interesting is the one with Vortex seemed to have a very light brown optical coating on the objective while the Viper HD's objective coating was more deep purple/red which is more typically seen in binoculars. I asked Vortex what the differences are between these two samples. Here is their response:
"There is no difference between the two, it was simply due to a copyright issue within the country of manufacturing - instead of halting production while it was addressed they elected to just change the label.
Coatings on lenses can be different colours depending on how long it took the coatings to dry, which can be impacted by a number of different factors. There is no actual difference to the coatings, and it will have no impact on the optical function of the lenses."
They did this on the 2016 Diamondbacks as well and changed the focus knob which was a bit sloppy when it first came out. My only guess is they found some issues with manufacturing and changed the label to distinguish the new from old.
Their explanation regarding the different colour coatings is interesting as well. I'm no expert when it comes to this so I would like to know what others think. I'm almost wondering if the first release wasn't even fully multi-coated as they claim. These are all made in China.