Server crash on start, class already loaded

Hello,

Attempting to add sponge to current forge install (FTB beyond 1.8.1 for MC 1.10.2) and getting he following error:

du -hxa --max-depth=1 | awk '{printf "%s %08.2f\t%s\n", index("KMG", substr($1, length($1))), substr($1, 0, length($1) -1), $0}' | sort -r|cut -f2,3


SpongePowered MIXIN Subsystem Version=0.6.10 Source=file:/home/AMP/.ampdata/instances/MCMA/Minecraft/mods/spongeforge-1.10.2-2281-5.2.0-BETA-2401.jar Env=SERVER
main/INFO - Sponge 06/19/2017 15:48:08
15:48:08/* */
/* An essential class was loaded before Sponge could patch it, this usually means */
/* that another coremod has caused the class to load prematurely. */
/* */
/* Class Name : net.minecraftforge.fml.common.ModContainer */
/* */
/*----------------------------------------------------------------------------------------------------------------------------------------------------------------------------*/
/* */
/* Loaded forge classes: */
/* */
/* net.minecraftforge.fml.common.DummyModContainer */
/* net.minecraftforge.fml.repackage.com.nothome.delta.SeekableSource */
/* net.minecraftforge.fml.common.FMLLog */
/* net.minecraftforge.fml.common.versioning.ArtifactVersion */
/* net.minecraftforge.fml.repackage.com.nothome.delta.GDiffPatcher */
/* net.minecraftforge.fml.common.ModMetadata */
/* net.minecraftforge.fml.repackage.com.nothome.delta.PatchException */
/* net.minecraftforge.fml.common.ModContainer */
/* net.minecraftforge.fml.common.patcher.ClassPatchManager */
/* net.minecraftforge.fml.common.asm.transformers.PatchingTransformer */
/* */
/*----------------------------------------------------------------------------------------------------------------------------------------------------------------------------*/
/* */
/* Technical details: */
/* */
/* Failed on class : net.minecraftforge.fml.common.ModContainer */
/* During phase : PREINIT */
/* Mixin : fml.common.MixinModContainer */
/* Config : mixins.forge.preinit.json */
/* Error Type : org.spongepowered.asm.mixin.transformer.throwables.MixinTargetAlreadyLoadedException */
/* Caused by : Unknown */
/* Message : Critical problem: mixins.forge.preinit.json:fml.common.MixinModContainer target net.minecraftforge.fml.common.ModContainer was already transformed. */
/* */
/******************************************************************************************************************************************************************************/
Attempting to shut down the VM cleanly

any information on how to get past this would be great. Not looking to heavily modify more than it is but was looking to use a few plugins.

Sponge has to be the first mod to load. Try using SpongeBootstrap to force this.