Two subs always better than one?

[bigmod]

I recently purchased a new sub for my system. A JBL E250P (12", 250W) to replace an old Jamo SUB200 (8", 100W maybe).

I am torn between keeping both subs or just keeping the newer one.

I read that 2 subs help average the dips and peaks of bass caused by the room's acoustics. However this is usually when both subs are the same.

So to any experts or anyone that has tried two different subs, what do you recommend?

Thanks.