I have added both relevant toys to my collection, but on different characters. Once I found out that the achievement needed you to get them both on the same character, I started running my alt characters through the quest for the Stolen Present, and am up to at least 144 attempts at this point this year. None of my characters have seen either one drop. I have seen almost all of the other past year presents drop, but those are two of the few I have not seen yet.
Looking into other resources, I have found some suspicion that once the items have been added to your account collection, they don’t drop for any of your characters. I have not seen any reported cases of the toy dropping on an account that already had both toys, either with or without the achievement. At most, I have seen a few comments from people reporting that the achievement was granted to them by posting a ticket after having both toys.
Achievement "They’re both footballs? https://www.wowhead.com/achievement=7852/theyre-both-footballs