If they are both healthy, which face it is very small, and if they are both performing as they were before being injured, then yes they would start both as they are currently their best players down low.
I would imagine their rotation would be something like this
C - Bynum 25, Varejao 15, Zeller 8
PF - Varejao - 15, Thompson 20, Zeller 7, Bennett 5
SF - Clark 24, Bennett 19, Gee 5
SG - Waiters 35, Jack 10, Gee 3
PG - Irving 38, Jack 10