I will enter a Nether Portal on Singleplayer or Multiplayer and I will come out at random places in the overworld! I will re-enter and be taken somewhere different again. Me and about 10 of my friends that play Minecraft have noticed this. We have Vanilla Minecraft.
Related issues
Comments

Duplicate of MC-1403.
Now when you say random places, do you mean with portals? Or are you ending up in places with no portals?