Your way would be Java. See stackoverflow: https://stackoverflow.com/questions/653861/join-two-wav-files-from-java
And this library would probably be helpfull: http://www.sauronsoftware.it/projects/jave/
But no easy task if both music files have different encoding.
I just realized that there is a BINARY data type.
Would there be a way to simply concatenate two binary fields (just like strings)? That would 100% handle this request.