Resolution: Works As Intended
Affects Version/s: Minecraft 1.7.9, Minecraft 14w20b, Minecraft 14w27b, Minecraft 14w29b, Minecraft 14w30c, Minecraft 1.8, Minecraft 1.8.1-pre4, Minecraft 15w37a, Minecraft 15w49b
Fix Version/s: None
Latest Java version, Windows 8.1
Firstly I should say I have opened this bug before a few years ago. But because there was much confusion on how to replicate the bug, it was eventually closed by the mods. Now I have a quick way to replicate it which is described at the end. I'm 100% positive this is a (minor) bug, so my request is to take it seriously!
A seed is supposed to generate exact the same world on all PC's. But some world chunks seem to have more versions. So most of the world is the same, but in 50% of all instances the seed is used to generate a new world, the seed is different. This is visible in the 2 screenshots I uploaded. There are two versions of this wall: one with coal in it, one with far less coal in it.
I discovered it this way: I was playing along with an LPer with the seed "1862394111". The world was the same, but upon seeing this wall, he had the version with many coal in it, I had just one coal spot. When playing along further, there were more instances (differently placed trees, pools, landscaping). This is kind of frustrating because when an LPer discoveres for instance a diamond chunk, it may not be there in my world. This happens with every seed. So every seed has some differently generated chunks.
How to replicate this:
1. Make a world (use the seed "1862394111" or "1862394111" for verification)
2. Go to the coordinates specified on the screen
3. Observe the wall
4. Recreate the world, like ten times
5. Around 50% of the time, the wall looks different. This affects some other chunks as well and affects every seed.
- I didn't quit and reload during playing,
- I tried it at my parents house as well. 50% of the time, the wall was different. So a seed seems to have at least two versions of some chunks.