every minute I have something like this.
on dedicated server with forge 1208 and IC2 633

[18:42:43] [Server thread/WARN] [IC2]: EnergyNet.addTileEntity: mekanism.generators.common.tile.TileEntityHeatGenerator@7c325728 (mekanism.generators.common.tile.TileEntityHeatGenerator@7c325728) is still conflicting with mekanism.generators.common.tile.TileEntityHeatGenerator@208d16e0 using the same position (overlapping), aborting
[18:42:43] [Server thread/WARN] [IC2]: EnergyNet.addTileEntity: mekanism.generators.common.tile.TileEntityHeatGenerator@227bc632 (mekanism.generators.common.tile.TileEntityHeatGenerator@227bc632) is still conflicting with mekanism.generators.common.tile.TileEntityHeatGenerator@7b846158 using the same position (overlapping), aborting
[18:42:43] [Server thread/WARN] [IC2]: EnergyNet.addTileEntity: mekanism.generators.common.tile.TileEntityHeatGenerator@7ac3b84f (mekanism.generators.common.tile.TileEntityHeatGenerator@7ac3b84f) is still conflicting with mekanism.generators.common.tile.TileEntityHeatGenerator@2c56a332 using the same position (overlapping), aborting
[18:42:43] [Server thread/WARN] [IC2]: EnergyNet.addTileEntity: mekanism.generators.common.tile.TileEntityHeatGenerator@2496a70b (mekanism.generators.common.tile.TileEntityHeatGenerator@2496a70b) is still conflicting with mekanism.generators.common.tile.TileEntityHeatGenerator@e439c94 using the same position (overlapping), aborting

Fixed in latest

still have the same issue with build 100 and IC2 build 645

I'm unable to replicate this, but on a hunch re: every weird annoying bug, I'm gonna say try chunkloading the areas with Heat Generators in them. Let us know if that has any effect.

change nothing when I try chunkloading the areas
now I have also a Input/output error but I don't know if it's related to mekanism. I have update a few other mods in same time.
http://pastebin.com/raw.php?i=98pqJe46

I can give you the server folder and the launcher if you want

sorry for my english