Multiply Ro Bin

Steps to Reproduce
First I place the egg on my shelf in my house. And I go out to travel, when I come back, there's Ro Bin standing in the house and he pukes out his stone for me. At the same time, the egg still on the shelf and wait about 10 seconds, it produces another Robin and stone. I have to remove the stone to the outside of my house. I catched a squirrel and kept it on the trees I plant. And the sister keeps aggro towards the squirrel even though it never attacks me. Not sure if this is another bug. When the squirrel dies, it drops Gizzard stone again!! And I lost count so there's a Ro Bin left in my house without a Gizzard Stone.