1. if you have a PA module that is rated at 1kW, its an amplifier, yes? so its input power will be less then this, say, 300 watts? So what would happen if you feed 1kW into an input stage rated at 300 watts?. What the typical configuration is, would be one PA module as a driver feeding say 4, 5 ,6? PA amplifiers that feed the output.
2. You still have not let on what frequency you are using or if you want a linear amplier or a class C.
3. If you have two PA amplifiers, one of which is delivering "full" power and one less. then sitting at the collector of the low power amplifier, when the current reduces, its voltage increases( due to its own RF) but the voltage also increase due to the incoming excess RF voltage from the full output PA. This increase in voltage will then produce unwanted effects.
Frank