IDE 1.6.12 serial plotter question

Does anyone know if there is any special method to split data or present it to the serial plotter in 1.6.12 ?

Can it present single or multiple streams ?
What will it do with other serial print data eg.

Serial.println("Failed to read from sensor!");

I have had it present two streams where no other serial print was involved but that’s it so far.
Just want to get to grips a little with this new toy they included.