Yes, as Josh said, they look similar, but are designed for different purposes.
The BeeQuiet has a minimum input impedance of about 50K, the Submissive is about 20K.
Essentially, the Submissive will put a more onerous load on your sources than the BeeQuiet, and since you don't have any long cables coming out of the BeeQuiet to drive the 300B, there isn't any real need for this. Due to the complexity of the resistor arrangement, there isn't any kind of workaround that I can think of to address the impedance issue without really mucking up the step sizes.
If you can get the guts out of the Submissive, they will work in the BeePre, but it won't quite match the performance of the BeeQuiet. On the other hand, if you damage a switch during removal, you'll wish you'd nabbed the BeeQuiet anyway.
-PB