Hi
I have some question but I think that only someone from Epic can answer me.
I made some animation with Matinee and I am using lot of particle emitters in the scene. No when I make movie throught Matinee I will have the same patter. All the particle would match 1:1 , frame by frame so I can render milion times and my image will looks the same. Now the fun part begins. When I slightly move my camera I have different results from the particles. For example rain drops will be different than from the camera before etc. BUT when I will render this many many times, it will be the same. It looks like camera movement has something to do with RNG of the particles. If you wonder why do I need this, well I need it for stereoscopic rendering 
without this I cant have 3D images. I guess that this is a deep-core problem(?). This is really strange but it is very crucial for me (and my company) to have it working properly.
Hope to hear someone about this issue.
Cheers,
Lucas
thank You!