As is well known by now, the dub of Pokémon Advance Generation changes the symbol on Ash's badge case to a rectangle. Looking at the recent episode, I have thought of a possible explanation for this. While it is odd that the same symbol is on May's bandana and never edited, have a look at Ash's t-shirt:
So I think that someone at Kids WB thought that the kids would get confused about who the case belonged to and told 4Kids to change it. Yes, it's stupid because the t-shirt is usually hidden but Ash was running around without his hoodie a few episodes prior to the first edit, so they did know it was there:
^Screenshot found at Serebii.net^
Don't forget that even 4Kids didn't think the edit was necessary as it was initially only in the Kids WB version.
Well, it's as plausable as anything else linked to Kids WB...
So I think that someone at Kids WB thought that the kids would get confused about who the case belonged to and told 4Kids to change it. Yes, it's stupid because the t-shirt is usually hidden but Ash was running around without his hoodie a few episodes prior to the first edit, so they did know it was there:
^Screenshot found at Serebii.net^
Don't forget that even 4Kids didn't think the edit was necessary as it was initially only in the Kids WB version.
Well, it's as plausable as anything else linked to Kids WB...