2 drivers in a box designed for 1

I found some amazing info here @ the12volt, so I thought I would try out the forum as well.  Admittedly, my post has nothing to do with car audio, but I figure the principle of tuning an enclosure is the same regardless of application.  You all seem to understand that better than the PRO Audio folks I have talked to.

I am building a compact bass guitar cabinet, which will be running at full range, but want to get the most thump possible, and I also need it to be LOUD!  I want to build a box intended for just one 10" driver, properly sized & tuned (I think I’ve got that covered)  Then, purely for added sound levels, I want to cut another hole in the box and put in a second identical driver.

Will that just muck the whole thing up?  Will the second speaker cancel out the proper tuning of the first, or is there additional tuning (without resizing the enclosure) that can be done?  If I only effectively get the low end of the one speaker, I am fine with that.  I just don’t want to take away from it.

Thanks in advance, as well as my advanced apologies for being dense.

Thanks haemphyst, that is exactly what I was looking for!

My goal is to keep the box as small as possible for portability, hence jamming two drivers into a box designed for one.  My amp should do the trick of of powering them, 1000 watts @ 8 ohms, and the drivers I was looking at were 4 ohms.

Luckily I have not purchased the drivers yet.  I think I found some from Eminence that are designed for small enclosures.  Plus, Eminence posts recomended enclosure designs!

I may not be able to get as small as I want, but it is a fair trade off for quality sound!

Thanks again!