I've got perhaps an ignorant question about mp3s and how Cubase handles them.

If I use a 128k mp3 sound file in Cubase (or any other platform) and save the new file as a 128k mp3, does the software compress the 128k audio again?

In other words, do I end up with a 128k sound file that has been compressed twice? (128k treated as the "original" and copressed again)

I imagine that the software is "smart enough" to know not to compress the file again but just wanted to be sure.

Thanks in advance,
Anton