Twin sub configuration - can you mix generations?

I’ve got an older surround setup and have recently purchased Arc, Era300s and Gen3 Sub. I’ve read that you can run two subs as a config for home theatre but can you mix generations? My older sub is a Gen2.

I’m still weeks away from setting everything up .. I need to reinforce a wall for the bigger TV and it won’t stop raining where I live :(

Obviously I’ll find out when I connect everything but I’d like to know while the discounts are active.