[tacman7]

Some VSTi's can accept more than one channel input so you can have a track for each channel.

You can have multiple tracks going to one instrument(midi tracks like riciebee says).

But that might not have the effect you want, a synth can't do two things at the same time usually.



Create another instance of the plugin, or record the sound of the plug/turn it into a wav file which would free up the synth.

I guess you can do that with freezing but I'm not too up on that.