I'm using Minecraft 1.6.4 and Forge 1.6.4-9.11.965 and putting together some mods, and I found item ID conflicts. So I go in and start reassigning IDs in the conflicting mods. However, Minecraft is registering the IDs as a different number. I used the NEI data dumps to sort this out.
The mods I've found so far that do this are Mariculture (example below), Farlanders and LogisticsPipes|Main. Odd thing is that the blocks IDs will match between configs and data dumps, but the item IDs are shifted by 256.
Is this an issue I can fix so that the id in the config is the id in the game?
If not, can I just assign the id in the config with a value that is 256 less? In the Mariculture example, I have blocks with IDs 1042-1070 and items with ids 1071-1145. If I were to start the items at 814, would that work just fine and not conflict with other items/blocks that are actually in those spots?
Its a old problem, that is ether a bug in the mods or in forge, but there is nothing you can do to fix it. You just have to figure out what mods shift the ids, and when you set item ids to those mods, make up for the shift.