Why are hydraulic roller lifters, different on different sides in the engines?

Ahhh... here we go! :)
No, you don't have to take them apart.
When I first googled this I found this forum & a guy showing the same thing so I reckon it aint only Euro cars that had it.

SO WHAT ABOUT this then: would it be better to have harder or softer springs in the lifters???

(& post #8: cool pic you have, I always fancied the -62 Darts, had one too, also a Savoy & a Fury of the same year.)