Yes, you can have both subs hooked up to a mono channel.
The way you wire them will be dependent upon the impedence rating of your amp and the nominal impedence rating of the subs.
It is likely your Explod amp is limited to 4 ohms mono (unless it is one of the first Gen. series, produced in the late '90s).
If your sub has two terminals (one +, one -) where the speaker wires are connected it is likely a 4 ohm driver.
In that case you can run the single sub directly at 4 ohms, or two at 8 ohms mono by wiring them in series (+ from amp to + term on first sub, - from amp to - term on second sub, - and + terms from both subs hooked together). While your amp will put out the same wattage either way, you will get different bass response depending upon the amp wattage, type of subs and box configuration.
You can try both ways and see which you prefer.
Bandpass boxes are capable of reproducing specific frequencies quite accurately and they are usually set up to output at a low resonant frequency that you and everybody else can feel.
If you want to feel as much bass as possible, bandpass is the way to go.
If you want to hear as much bass as possible across the bandwidth and reproduce music much more accurately, a well designed ported box or a sealed box are superior choices.
