They are not a breeder, they are a reseller of bulk Spanish seeds. Their advertising and marketing is decent, but they do not have a sterling reputation as a source for high quality seeds. Some have had decent results with their gear but there are a number of threads here and on other sites with not so happy customers.
I’ve personally grown out their seeds that were given to me and got ok but not spectacular results. With so many other sources these days available in the US, most growers stateside would not recommend them. YMMV though. Popping seeds and growing weed is fun for me no matter the source. I grow for myself and friends, it’s not an income stream for me.
I’m not shitting on Crop King but also am not raving about them and recommending them to all my internet friends.
To the OP, you’ll see some variation in almost any pack of seeds, regardless of where they come from. NL is an old school strain but there was some pretty strong breeding behind the early versions of it. Depending on the actual version, there were some that were that were pretty well stabilized and gave remarkably consistent plants from seed to seed in a pack.
That was 30 year ago tho, no idea of how closely the Crop King branded stuff today resembles the old school breedings. Strong second on the AK Bean Brains gear if you’re looking for good old school NL genetics.