talkin' 'bout my variations

sometimes i wonder what went on in the topps factory or cantina or wherever sy and his guys decided on what cards to print. i say this because i don't understand photo variations.  in 1991, there were several 'error' cards featuring the wrong player photo (jose gonzalez/billy bean for example) that were corrected in later print runs.  i guess i always figured that they print the cards, pack 'em up, ship 'em out and that's it.  no more printing (unless you're upper deck, right?).  sure, you can print another series, as topps did early on and as they do now, and i know sometimes base cards of players are included in more than one series (eg 2009 stephen drew), but why would you print new versions of cards from the earlier series? 

anyway, i am thinking of 1962 in particular.  here's wally moon's base card

pretty exciting stuff.  hatless, but at least he's in a dodgers uniform.  we can't say the same for ol' lee walls on his card.

i think we've decided that's a cubs jersey, for whom walls last played for in 1959.

ok, those two cards are typical 1962 topps cards.  neither moon nor walls changed teams that year, so why did topps do this:

same number on the back, but a different photo (obviously).  i like it though, since it features more of the uniform.  maybe topps would update lee walls' uniform, too, right? please? well, yes and no.

again, it's the same number on the checklist, and he's still hatless, but now he's in what i believe to be a phillies jersey (his 1961 team).  baby steps.  this card also shows off the fantastic green tint that some of the cards in the second series were printed with.

now don't get me wrong - i love variations.  i just wonder, why these cards in this set?