That is correct young Jedi and no software will overcome that. You need two radios to be able to run them concurrently. Unless you devote all your CPU cycles to some kind of multi-plex scheme or swap soft radios. Even then there is no telling how a network would act if you were rapidly switching. It would pro'ly just drop you completely until the tower received a stable signal.

Motorola introduced quad radios in a handset 2 or 3 years ago. But that was on iDEN and you were still identified by a single electronic serial number (hashed from 1 SIM). The radios were/are used primarily for packet data. Nextel shut their WiDEN system down because of capacity issues but their are plenty of private networks in airports, or on large business, and university campus's that still use it.