Bug Millenaire duplication

[Xombie11]

when I try adding millenaire to the monster mod pack and then loading it up I get a message saying that
'Forge Mod Loader had found a problem with you minecraft installation
You have mod sources that are duplicate within your system
Mod Id : File name
millenaire : minecraft
millenaire : millenaire-jar-51.11'

I've tried looking online and I've found a few topics about it in this forum and another forum but none of them had a solution one of them had a post that mentioned something about using multiMC but didn't say how I was wondering if anyone knew what to do?

 

[McJty]

Check your mod folder and see if you didn't accidently put the millenaire mod twice there. For example maybe you put both the client and server version in your mod folder?

 

[Xombie11]

the only millenaire mod folders I have in there are Millenaire, Millenaire-Custom and Millenaire-jar5.1.11 all three of which the instructions said to put into the mods folder