That actually doesnt surprise me, the same 2 of anything can produce multiple "phenotypes". I think of a batch of seeds as like a liter of puppies and they may be similar but they will be different and occasionally there will be "were did that come from" pup show up, of course they are usually the top shelf pup. Think about how many WP members have grown Aurora Indica and think about how different they looked, I bet they smoked a little different too. 

My question is did they advertise for test subjects and where do they advertise for them 

"The study analyzed nearly 90,000 samples of cannabis across six states"