Hello together, I use Boinc with Seti@home. Up to now I got always 2 Workunits. As I can adjust which I several Workunits get can.
I think you are asking how to download more units than the current two you have. Go to your account and then to general preferences and extend the "time to connect". The minimum is .1 days the maximum is 10 days, the longer you make it the more units your computer will download.
You are posting from an account that does not have any computer connected to SETI, so we can not determine anything about how your computer might be working.
Are you asking can you crunch more than 2 simutaneously? Depends on the processor, but usually the answer is no.