I'm not familiar with farming where you are, but I imagine that English/Persian (what you called "common") walnuts are more common there, so it's likely one of those. English/Persian walnuts release juglone, but I've read that it's far less than black walnut or butternut.
The effects of juglone seem to vary quite a bit based off of climate and soil type too. Where I live in the Pacific Northwest of the United States, I've never seen or heard of a case where walnuts, even black walnut, stunted the growth of other trees. That doesn't mean it doesn't happen, but I've also heard from
people who have worked with food trees for decades that they've never seen it either.