[MM] duplicated entries in definitions

I am generating `api.yaml` file using `autorest.cli` with input file: `azure-rest-api-specs\specification\compute\resource-manager\readme.md`

# Tag in use
`package-2019-07`.

# Cli section added in `readme.md`

``` yaml $(cli)
cli:
cli-name: compute
azure-arm: true
license-header: MICROSOFT_MIT_NO_VERSION
payload-flattening-threshold: 2
namespace: azure.mgmt.compute
package-name: azure-mgmt-compute
clear-output-folder: false
debug: true
disable-azure-cli: true
```

# Problem encountered

The generated `computevirtualmachine/api.yaml` contains two entries with same name `list_by_subscription`:
```
list_by_subscription: !ruby/object:Api::Azure::SDKOperationDefinition
go_func_name: ListAll
python_func_name: list_all
request:
list_by_subscription: !ruby/object:Api::Azure::SDKOperationDefinition
go_func_name: ListByLocation
python_func_name: list_by_location
request:
'/location': !ruby/object:Api::Azure::SDKTypeDefinition::StringObject
go_field_name: Location
python_field_name: location
```