it's likely a matter that you can have a geode drop slot for both day and weather separately, but because weather overwrites day, the day drop's would be altered, and most likely, if weather's active, it's more likely to use that drop slot instead of day, even if one is waiting on the 5 min timer and the other isn't, but there's a very low chance that the day's drop will get through instead, and thus give you two in less than 5 minutes. That's purely speculation, though.