400 Bad request when "Generate random datapoint"

In the "+ Generate random datapoint" click event of http://localhost:3000/datastreams/

```
Each child in an array or iterator should have a unique "key" prop. Check the render method of `Datastream`. See https://fb.me/react-warning-keys for more information.
in div (at Datastream.js:33)
in Datastream (created by Connect(Datastream))
in Connect(Datastream) (created by Route)
in Route (at App.js:26)
in div (created by Container)
in Container (at App.js:22)
in div (at App.js:17)
in App (at index.js:33)
in Router (created by ConnectedRouter)
in ConnectedRouter (at index.js:32)
in Provider (at index.js:31)
```

and also the transaction fails with
```
POST http://localhost:9984/api/v1/transactions 400 (BAD REQUEST)
```

is this a known issue? I can help to fix this if needed.