OP. You might want to do some more studying on how the MP works. It doesn't look like so much a bug, but lack of primary network development.
The container is creating both objects. However based on our design logic there are flaws.
1. The host only creates 1 Container set(ie both sprites)
2. The client creates 2 Container sets. The blue sprite is covering the first one and the green sprite is -1000,-1000. This results in the look that the green sprite isn't being spawned.
Seriously while c2 MP plugin I think is the easiest. You both might want to consider going through the tutorials of just C2 core learning tuts. Rather than jumping into the MP.
*here are some stuff
*You don't sync objects to peers
*there is no peer tracking
*don't assume that containers fall into a shape. Assume they are off screen. So always make sure to set there position.
* since the client get's 2 instances and the host gets 1 instance of your object your not handling peer connections.
I get the feeling there is a lot of guess work going on in this MP capx. I don't see a bug. Just not a solid logic flow and proper use of the MP plugin or C2 moderate functionality.