For those players who end up getting lots and lots of duplicates of certain decorations and not enough (or none) of another, perhaps a "Trading Post" building might be worth considering. Players could put up extras of certain decorations that were won/received during various events. It would only be decorations, though--no pets or pet homes. Also, if we missed certain decorations from previous events, we could also trade those around as well, but only with decorations from those events (so, no trading Halloween stuff for Valentine's Day stuff). There could be a checklist unique to that particular even that we could select our desired trade items from. It could be a 1-to-1 trade, or perhaps it might be based on how many spaces the particular decorations takes up. Using the Easter 2016 event as an example, it might be 1 cow egg for 1 Easter basket, or 2 cow eggs for an Easter wagon.

It might be a pain to do, but if someone really wanted a lot of cow eggs and only got the 1 that is a prize from one of the goals, this could be a way for that person to collect a herd of cow eggs.