Yep, you can be on multiple polices. I'm the main driver on 2 cars and was a named on a 3rd.
You can't spread your current NCB over multiple polices though. For example my Celica carries the 10 years NCB, the Supra has 0 NCB but the insurer can take into consideration the main bonus so doesn't price me up like a new driver. I still found keeping to the specialist insurers cheaper than going muliti-car. I couldn't get classic on a modified import, so pay just over £400 fully comp on limited mileage.
If you want to spread the cost of all the car policies you could always get a new 0% purchase credit card every year. Very handy instant loan on anything. Just don't miss a payment or the deal's off.