I've got this two column database that lists gene codes and then biological pathway. Within the database some gene codes are linked to multiple biological pathways:
      A           B
    396139  mesonephros development    
    396139  camera-type eye development  
    396139  Sertoli celldevelopment
I'm trying to get rid of these repeats, while moving each biological function to a new column:
  A       B                         C                           D
396139    mesonephros development   camera-type eye development Sertoli celldevelopment
I've tried a few macros in Excel, but have been unsuccessful in making anything constructive. I'm also a little new to R so I have no idea where I would start to format this. Any help in either software would be much appreciated.
This question is different from the claimed duplicate because they are trying to combine columns when I require them to be separate. The answer in this question is also simpler and does not require an external package and is, therefore, worth keeping separate.