Yes, 4 resistors means you can have 4 times the power dissipation (as long as it's sufficiently symmetrical). Remember P = U * I
If you put two resistors (same ohms value) in parallel the voltage across stays the same, but the current gets divided in half for each resistor, meaning the power dissipated in each resistor gets divided in half.
Same goes for two resistors (same ohms value) in series, while the current stays the same the voltage drop across each resistor gets divided in half, meaning also the power dissipated in each resistor gets divided in half.
The 2 x 2 = 4 resistors arrangement divides both U in half and I in half for each resistor meaning the power dissipation in each resistor gets quartered.
Paralleling zeners and expecting them to share the current wont work. Due to the extremely non linear characteristic of zeners and diodes in general, minute differences in zerer voltage (even caused by temperature differences) will result in hugely different currents. That's why paralleling up LEDs without series resistors won't work, the resistor because of it's linear characteristic will somewhat mitigate the nonlinear characteristics of the diodes.
Now I don't understand your circuit, but if there is a series resistor in the current path of your zener diode, you might be able to divide it also up into two, which would help share the current across two zeners. But since the current rating isn't even known, I don't know if two zeners are required or enough.
Boy that was a long post for a whole lot of nothing.