it's because you cannot manually order collectibles in your inventory, they are ordered by date.
so in the case of the trade I just did with you, before my inventory looked like this:
[sakura] -> [galaxy egg] -> [aurora egg] -> [sakura] -> [dreamy egg]
and when I did the trade, I got the sakura to go in between my galaxy and aurora egg, so that my inventory collectibles are more symmetrical.
as for messages, well if you're on the desktop site you can hover over collectibles and if they're gifted, it'll say who gifted it, along with a message if applicable. I usually ask for messages but most people can't come up with one and lately I haven't been able to either haha. might make a separate thread later asking people to put messages on my gifted collectibles.