Yes, both the Analog Baron will appear as a separate aircraft in the aircraft selection menu, while the Baron Improvements Mod modifies the default aircraft directly.  You will still be able to fly the modified G58 Baron, and the Analog B58 Baron.  This question specifically pertains to the “Baron Improvements Mod”.  There is no guarantee that other mods will not modify the core G58 Baron files that the Analog Baron depends on.  Should this occur, it will most likely affect only the sounds of the Analog Baron, and a compatibility mod is always possible.