make a box for 2 subs dual sub winisd?

Hi all,

First, just wanted to say this is a great site and a great forum.  Lots of excellent info here.  Now I did try to search but it seems I am the only one that is having a problem figuring this out. I must be more obtuse than the people who are getting errors trying to fill out their driver specifications. 

Anyhow, my problem is this: I'm trying to design a vented (ported)  box for 2 10" subs using winisd.  Now the problems I'm having are twofold:

1. What type of box is the one where each each chamber for each sub is sealed off from the other?  This is the type you use so that in case one sub fails, you won't blow the other sub because of the difference in air pressure and all that.  I'm not sure what that is called in WinISD.

2. With regards to ports and tuning - How does that work in a dual-speaker box?  I figured that I could start with port number 1, enter my values, then choose port number 2, enter the same values, and it would work.  My thinking was, port 1 for chamber 1 for sub 1, and port 2 for the other chamber with the other sub.  But that doesn't seem to be how it works, because when I enter values for port 1, then switch to port 2 and enter the same values, when I switch back to port 1, the value for the length (at least, sometimes diameter too) has changed to something really wacky! what is the deal with this?  How do I properly set up the ports (round in this case) for my dual-speaker box? Or do I have to treat each chamber as a single enclosure and just model it as a single speaker box?

Thanks in advance.

Fair enough, just wanted to make sure.  Thanks for the response!