That will concatenates files the files, not the content of encoding envelopes.
If you concatenate two wav files you will get a file with a wav header at the beginning and another wave header somewhere in the middle. The first header will indicate a data chunk size of the original wave 1. When you play back, either the player will stop at the end of the first specified data chunk or it will play through with noise where the second header is. Or the player may reject the file because the header indicates a size that differs from the size of the file in it's directory entry.
You need a sound editing program.