Castle m8, Er..no you can't do that, it won't work. You can only use one dsl modem on a telephone line.
If you want to share your internet connection between a couple of computers, best simple way is to network the two pc's together and share the internet connection from the machine which is currently connected to the outside world.
There are several ways to achieve this, have either of your machines got a network adapter fitted already? If they both have wired adapters you can just purchase a cross-over network cable plug in and configure, hey presto....
You could go wireless if you want...more questions later, see what you've got first...
Have fun