Minecraft crashing

hi whenever i try to launch in to minecraft with forge 1.12.2 it crashes with my mod in the folder when i do it without it and have only optifine it works this is what it told me and also i wasnt able to test it before cause i had the same problem with it it would crash any help please? and my mod is 1.12.2 on the m creator version 2020.2

The game crashed whilst initializing game
Error: java.lang.IllegalArgumentException: Multiple entries with same key: moreores=FMLMod:moreores{1.0.0} and moreores=FMLMod:moreores{1.0.0}. To index multiple values under a key, use Multimaps.index.