(Believe this has been about since 0.15, but I have seen it in current v1.0) In Realms.

Feeding animals will cause the feed (seeds, carrots, potatoes etc) to overwrite an inventory slot item with a duplicate group of feed.

Attached is an image. (I have a video of it happening too).

Description to reproduce the issue, along with the image.
I have 42 Seeds in my 7th action bar slot. (red circle)
A carrot is in my 7th inventory slot. (green circle)

When I feed a chicken some seeds, the carrot in the green circle will be overwritten with 41 seeds. The original 42 seeds remain.

Thanks.