if they are multi sourcing the sticks just like dualsense and PS5/PS4 fans, then it goes back to your luck.If it's 2 for $20, then there goes hope they'd be of better, non drifting quality.
I'd think it's the price of a single stick unit, the modules are identical on both sides, or are they?
got ALPS? yay. probably last almost forever (like my xbox360 wired gamepad that still i use today)
got the weird-looking Y brand (or whatever thats not alps)? it'll drift even if you baby it. (like my dualsense)