[MdDatepicker] Error on open

[epileftro85]

Steps to reproduce

Just initialize a datepicker like in docs.

Which browser?

Google Chrome (not tested in others).

What is expected?

not throwing this error.

What is actually happening?

[Vue warn]: Duplicate keys detected: '1'. This may cause an update error.

found in

---> at src/components/MdDatepicker/MdDatepickerDialog.vue
at src/components/MdField/MdField.vue
at src/components/MdDatepicker/MdDatepicker.vue
at src/components/dashboard/UserFields.vue
at src/components/dashboard/createUser.vue
at src/App.vue

warn @ vue.esm.js?efeb:578
checkDuplicateKeys @ vue.esm.js?efeb:5779
createChildren @ vue.esm.js?efeb:5583
createElm @ vue.esm.js?efeb:5488
createChildren @ vue.esm.js?efeb:5586
createElm @ vue.esm.js?efeb:5488
createChildren @ vue.esm.js?efeb:5586
createElm @ vue.esm.js?efeb:5488
patch @ vue.esm.js?efeb:5995
Vue._update @ vue.esm.js?efeb:2637
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
Watcher @ vue.esm.js?efeb:3104
mountComponent @ vue.esm.js?efeb:2772
Vue$3.$mount @ vue.esm.js?efeb:8429
Vue$3.$mount @ vue.esm.js?efeb:10790
init @ vue.esm.js?efeb:4065
createComponent @ vue.esm.js?efeb:5512
createElm @ vue.esm.js?efeb:5460
patch @ vue.esm.js?efeb:5995
Vue._update @ vue.esm.js?efeb:2637
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
Watcher @ vue.esm.js?efeb:3104
mountComponent @ vue.esm.js?efeb:2772
Vue$3.$mount @ vue.esm.js?efeb:8429
Vue$3.$mount @ vue.esm.js?efeb:10790
init @ vue.esm.js?efeb:4065
createComponent @ vue.esm.js?efeb:5512
createElm @ vue.esm.js?efeb:5460
createChildren @ vue.esm.js?efeb:5586
createElm @ vue.esm.js?efeb:5488
createChildren @ vue.esm.js?efeb:5586
createElm @ vue.esm.js?efeb:5488
createChildren @ vue.esm.js?efeb:5586
createElm @ vue.esm.js?efeb:5488
patch @ vue.esm.js?efeb:5995
Vue._update @ vue.esm.js?efeb:2637
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
Watcher @ vue.esm.js?efeb:3104
mountComponent @ vue.esm.js?efeb:2772
Vue$3.$mount @ vue.esm.js?efeb:8429
Vue$3.$mount @ vue.esm.js?efeb:10790
init @ vue.esm.js?efeb:4065
createComponent @ vue.esm.js?efeb:5512
createElm @ vue.esm.js?efeb:5460
patch @ vue.esm.js?efeb:5995
Vue._update @ vue.esm.js?efeb:2637
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
Watcher @ vue.esm.js?efeb:3104
mountComponent @ vue.esm.js?efeb:2772
Vue$3.$mount @ vue.esm.js?efeb:8429
Vue$3.$mount @ vue.esm.js?efeb:10790
init @ vue.esm.js?efeb:4065
createComponent @ vue.esm.js?efeb:5512
createElm @ vue.esm.js?efeb:5460
patch @ vue.esm.js?efeb:5995
Vue._update @ vue.esm.js?efeb:2637
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
Watcher @ vue.esm.js?efeb:3104
mountComponent @ vue.esm.js?efeb:2772
Vue$3.$mount @ vue.esm.js?efeb:8429
Vue$3.$mount @ vue.esm.js?efeb:10790
init @ vue.esm.js?efeb:4065
createComponent @ vue.esm.js?efeb:5512
createElm @ vue.esm.js?efeb:5460
patch @ vue.esm.js?efeb:5995
Vue._update @ vue.esm.js?efeb:2637
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
Watcher @ vue.esm.js?efeb:3104
mountComponent @ vue.esm.js?efeb:2772
Vue$3.$mount @ vue.esm.js?efeb:8429
Vue$3.$mount @ vue.esm.js?efeb:10790
init @ vue.esm.js?efeb:4065
createComponent @ vue.esm.js?efeb:5512
createElm @ vue.esm.js?efeb:5460
patch @ vue.esm.js?efeb:6034
Vue._update @ vue.esm.js?efeb:2647
updateComponent @ vue.esm.js?efeb:2765
get @ vue.esm.js?efeb:3115
run @ vue.esm.js?efeb:3192
flushSchedulerQueue @ vue.esm.js?efeb:2954
(anonymous) @ vue.esm.js?efeb:1813
flushCallbacks @ vue.esm.js?efeb:1734