Can several instances of Transmission "share" router ports?

[Klistvud <quotations@aliceadsl.fr>]

Howdie, fellow Debianites!

Now, this may be a silly question to ask, but anyway...
My home router is running out of redirectable ports, so I was 
wondering: what would happen if I just configured the default 
Transmission ports in the router and then let several users run 
Transmission concurrently? I mean, without changing anybody's settings 
from the defaults, so that all instances of Transmission used the same 
ports? Would the packets somehow "know" which instance of Transmission 
to reach, or would I just make a horrible mess? More generally: 
can the *same* ports be "shared" among simultaneously running 
applications or not?

P.S. I'm talking of users which are set up on the *same* physical box, 
of course (a Debian Lenny w/ Gnome desktop, on a 192.168.*.* home 
network) and can actually all be logged in at the same time using 
Gnome's "switch-user-without-logging-out" feature.

-- 
Regards,

Klistvud
Certifiable Loonix User #481801