Failed to load the css-edit-groups package

Nobody has claimed this yet.

[Enter steps to reproduce:]

1. ...
2. ...

**Atom**: 1.19.7 x64
**Electron**: 1.6.9
**OS**: DEVLAPTOP
**Thrown From**: [css-edit-groups](https://github.com/ekonstantinidis/css-edit-groups) package 0.4.2

### Stack Trace

Failed to load the css-edit-groups package

```
At Duplicate key 'cmd-l'

Error: Duplicate key 'cmd-l'
at Object.detectDuplicateKeys (:37511:19)
at :155202:44
at Array.reduce (native)
at Obj (:155194:36)
at transformNode (:155284:18)
at Value (:155166:20)
at transformNode (:155284:18)
at :155201:23
at Array.reduce (native)
at Obj (:155194:36)
at transformNode (:155284:18)
at Value (:155166:20)
at transformNode (:155284:18)
at Block (:155163:20)
at transformNode (:155284:18)
at Object.parse (:155290:18)
at parseObject (:37285:29)
at parseContentsSync (:37311:22)
at Object.readFileSync (:37413:20)
at :69761:44
at Array.map (native)
at Package.module.exports.Package.loadKeymaps (:69758:52)
at :69421:25
at Package.module.exports.Package.measure (:69371:21)
at Package.module.exports.Package.load (:69416:18)
at PackageManager.module.exports.PackageManager.loadAvailablePackage (:23563:22)
at :23477:25
at Config.module.exports.Config.transact (:20698:22)
at PackageManager.module.exports.PackageManager.loadPackages (:23471:25)
at :1048:34

```

### Commands

```
```

### Non-Core Packages

```
atom-grails 1.0.1
atom-latex 0.8.1
atom-material-syntax 1.0.6
atom-material-ui 2.0.4
busy-signal 1.4.3
css-edit-groups 0.4.2
intentions 1.1.5
language-groovy 0.7.0
language-groovy-cloned-from-java 0.3.0
language-latex 1.1.1
latex 0.46.0
latex-autocomplete 1.0.0
latex-completions 0.3.3
latex-friend 0.0.11
latex-hyperclick 0.2.0
latex-plus 0.9.1
latexer 0.3.0
latextools 0.8.5
line-count 0.5.0
linter 2.2.0
linter-spell 0.15.0
linter-spell-latex 0.10.0
linter-ui-default 1.6.8
pdf-view 0.59.0
script 3.15.0
```

Start by reproducing the package-load failure with Atom 1.19.7 and inspect the package's keymap entries for the duplicate `cmd-l` reported in the stack trace. Done means the css-edit-groups package loads without the duplicate-key error; no source file or test is identified in the issue.

Written by the indexing model from the issue text.