The question of simultaneouus or multiple discoveries was initiated  
by Robert K Merton in "SINGLETONS AND MULTIPLES IN SCIENTIFIC  
DISCOVERY - A CHAPTER IN SOCIOLOGY OF SCIENCE"  
PROCEEDINGS OF THE AMERICAN PHILOSOPHICAL SOCIETY 
105 (5): 470-& 1961. A huge literature in the "old" sociology of  
science grew from this paper by Merton. You can trace the influence  
of this paper at  
http://www.garfield.library.upenn.edu/histcomp/merton_p-am-philo- 
soc_v105_p470/ 
 
E. Roy Weintraub