1962 Topps pose variations -- why??

[geosluggo]

Has anyone read a good explanation for why the 1962 Topps set includes so many picture variations? I don't care about the "green tint" cards, which to me are a printing anomaly rather than a true variation. And I don't mean the Buhl and Tasby cards, where their caps were airbrushed in later versions because they were traded. I'm talking about the different pictures used for seven players, none of whom were traded. The Wally Moon holding a bat card is a lot cooler than the hatless portrait, but who decided the Lee Walls and Billy Hoeft cards needed to be updated with nearly identical pictures? And while it's admirable that someone felt the need to change the Angels team card to include two inset pics, can anyone even tell who those players are?

I can't think of any other year Topps did this. There are the separate Clay Dalrymple cards in 1969 after he was traded and the 1974 Washington/Padres cards, but no other deliberate picture variations come to mind.