Apple used to support a "universal binary" format[1] to run a "single" binary on both PPC and Intel processors (as well as 32 bit vs 64 bit). This meant that both the PPC and Intel code was inside the same file, but a specific section of the file was executed based on what architecture the computer was using.

Of course, modern Macs are 64 bit Intel only, so this isn't really necessary anymore unless a developer needs to support older platforms.

[1] https://en.wikipedia.org/wiki/Universal_binary