Need test case for duplicate entries in manifest.yaml

We need a test case for expected behavior when there are duplicated entries in `manifest.yaml` such as:

```
packages:
helloworld:
actions:
hello1:
function: ../src/integration/helloworld/actions/hello.js
limits:
timeout: 1
timeout: 600000
```

https://github.com/apache/openwhisk-wskdeploy/pull/1101 eliminated a similar test due to a package change and the behavior also changes.