SpoutDev/Spout — comment on commit 89a8cf6c58581597bbec2fd5f21303f1b6737ccb
File: src/main/java/org/spout/server/SpoutChunk.java line 526
By Raphfrk:

I think so.

An entity should be spawned, if an entity enters the chunk and the player was no observing the old chunk.