No, images with 4 columns are usually formatted for XP, and the first and third columns are exactly the same. I assumed the original image wasn't formatted for Ace, because it's got too many columns. I wasn't sure if the WAS formatted for XP because, as I said, I couldn't see any difference between ANY of the columns. So my "IF it's formatted for XP" was a safety check, indicating I KNEW it would be safe to delete the first one if the sprite was originally an XP sprite. If it wasn't, there's no guarantee the first column was the one that could be safely deleted.
This thread is being closed, due to being solved. If for some reason you would like this thread re-opened, please report this post and leave a message why. Thank you.