Block error?

[Staal]

I am currently trying to host my current server which has a few mods running on it already together with FORGE so I tried I give this a shot, but when attempting to do so I stumble on a big error so I was hoping of anyone could help me out here:


---- Minecraft Crash Report ----
// Oh - I know what I did wrong!

Time: 12/22/13 1:25 AM
Description: Exception in server tick loop

java.lang.IllegalArgumentException: Slot 3350 is already occupied by mods.natura.blocks.NFenceGate@74885304 when adding micdoodle8.mods.galacticraft.core.blocks.GCCoreBlockBreathableAir@22026761
at net.minecraft.block.Block.<init>(Block.java:349)
at micdoodle8.mods.galacticraft.core.blocks.GCCoreBlockBreathableAir.<init>(GCCoreBlockBreathableAir.java:26)
at micdoodle8.mods.galacticraft.core.blocks.GCCoreBlocks.initBlocks(GCCoreBlocks.java:78)
at micdoodle8.mods.galacticraft.core.GalacticraftCore.preInit(GalacticraftCore.java:244)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:545)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:201)
at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:181)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:112)
at cpw.mods.fml.common.Loader.loadMods(Loader.java:522)
at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:99)
at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:350)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:69)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:445)
at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)


This is the error I get, if anyone can help me out with this, It would be greatful.