From what I have read the amp will be fine pushing the higher impedance. They just don't like lower impedences. They say 8 ohm will be fine on a 4ohm stable amp. You will only get half the power.
Scroll down to helotaxi's post that has 2 4ohm svc = 8ohm load
That's how your wiring should be. I think you may have done what was said and dropped it to 2ohm. But they say most amps have some kind of protection built into them. What kind of amp is it ?
In all actuallity you would have been better off just running the one sub anyway. Getting more power from the amp is good and avoiding series wiring between subs is good as well.
Too late for that now, get yourself a 2 ohm stable mono amp for those subs.