2 subs, 1 chamber

Has anybody ever tried placing 2 subs (not isobarically) in an enclosure, sharing the airspace (ie 1 shared chamber for both subs, mounted regularly)?

My initial thoughts of this is that when placing 2 subs in a shared enclosure, it probably changes the characteristics of the sub, making the box size requirements different than the manufacture provided specs.  Is this correct?

What do you mean stronger sub?  What if both are the same subs, driven by the same channel on the same amp?

So, from what I gather, you guys are saying:

1) generally, not good to share a chamber

2) if they share the same chamber, the total space required is still the same as the total space in 2 independent chambers

.. hm..  if #2 is true, then, it really doesn't make sense to share a chamber (you're not saving any space). 

I guess what I'm looking for is a way to save space while using 2 subs.

I have 2 12" Orion XTR series 2 subs.  They require 1.5 ft^3 / sub in a sealed box, 2.5ft^3 in a ported. 

I'm planning on only using 1 sub in a 1.5 ft^3 sealed box, unless somebody can suggest a way to use both without causing too much of an increase in space.