Not sure, I've never tried to use forwards with more than one plugin subscribing to it. It's using the standard mechanism for SourceMod forwards, so probably the order the plugins are loaded matters.
You're using a ton of plugins that spawn things, chances are one of them doesn't know how to handle more than 4 players per team.
I think its this plugin that was causing problems. I am not 100% sure yet, I don't have time to test, but from watching chat logs no one is complaining of double smokers/no medkits/pills