The idea is that even when the key changes, the resulting code and compiled module can remain the same. We avoid this by keeping a hash of the C code (as well as of the compilation options) and when this hash matches that of an existing module, we re-use this module instead of having two different modules doing the same thing. Two improvements should be made to the current implementation: 1. Currently a module is still compiled before we detect that it is duplicated, while we should avoid this compilation step. 2. It may be the case that different code or compilation options actually lead to the exact same compiled module. It would be nice to be able to detect this situation as well.