The NEC does not differentiate between fiberglass or spray in foam. If you look at 334.80 in the 2008 NEC, the last paragraph requires an ampacity adjustment.

If you do the ampacity adjustment, you'll start in the 90 degree column and adjust that with a 70% multiplier for 8 current carrying conductors. That works out to 21 amps for #12 and 17.5 amps for #14, both of which exceed the maximum circuit breaker size for both sizes.

I'd say that there is no problem running 4 two conductor cables.

Tom

Few things are harder to put up with than the annoyance of a good example.