Well, there is a second place you can fight dr. salvador, but you have to be killer good to kill both dr. salvadors. there are two paths, when u get past that scene using the electronic bonoculars. If continue to take the path to the left that leads out of the village u will run into Dr. Salvador there too. If you are fast enough after killing him u can pick up the Ruby he drops, turn around and go into the 2 story house and face a second one. Fun as heck! XD
Conquering the world, one step at a time.