To address your concerns:

1. I assume that it's the same type of process because by default the PID file is being written to the current working directory of the script. If you'd like, you can specify a location yourself to ensure that each type of process is grouped on one PID file.

2. Out of curiosity, how would you go about doing this?

3. I think this would be really difficult to accomplish.

4. I agree if we could somehow figure out 2 or 3, that would be great.