I can't remember where i did find that : Amplitube is not working if you use more than one plugin in the same track template. (for all DAWs) the solution was to copy and rename the dll to use two amplitubes dll for 2 plugins. I don't know how to do it in reaper but i think you can rename the flugin fx, then copy the dll with another name (in your plugin folder), and reaper will find another one with the original name. I hope it helps... but i may be wrong...