If multiple bower instances are running, they access shared file system resources such as the cache. This may cause problems if two or more instance attempt to write to the same cache files among other synchronisations issues due to in-memory cache of each process.

While this is low priority, a solution must be implemented to solve this problem.
There are a couple of solutions, being file locks one of them.

This issue serves as a discussion for the problem and its solutions. If anyone has had this problem, please share what you did to solve it!