You are thinking like an Artist.
Scientists and Hackers (the original concept) try to solve a problem once and reuse knowledge and solutions.
Also remember that it is not only about you. It is about the community that surounds the projects. They will be divided.
Nevertheles, there are always other reasons related to
Project management. For example if the owner of the other project invest few time, reject many changes, etc..
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.