Fix environment key already defined

[jlosito]

This might be a duplicate of other pull requests. I do see some pull requests changing code around this area.

Even though this gets around the issue with the duplicate environment key already being stated, the application still does not stay up and running, but simply exits.

$ docker-compose -p habquickstart up -d
[+] Building 0.0s (0/0)                                                                                                                                               docker:desktop-linux
[+] Running 4/4
 ✔ Network habquickstart_default            Created                                                                                                                                   0.0s
 ✔ Container habquickstart-web-1-1          Started                                                                                                                                   0.0s
 ✔ Container habquickstart-web-2-1          Started                                                                                                                                   0.0s
 ✔ Container habquickstart-load-balancer-1  Started                                                                                                                                   0.0s

[mysteryegg]

These changes are reasonable and fix the issue from my testing. Not sure if I'm authorized to approve, but I'll submit feedback against the Learn Chef courses that this commit unblocks the guided exercises.
Note that in older versions of docker-compose, duplicate keys would overwrite each other instead of throwing an error, see docker/compose#5267

[SteveDelFante]

The merged fix seems to work now for the Learn Chef habitat tutorial.