Grafana ships with built-in support for InfluxDB releases >0.9.x.
There are separate data sources for InfluxDB in Grafana: the latest InfluxDB release and InfluxDB 0.8.x that Grafana maintains support for as a convenience for its existing users. InfluxDB no longer maintains release 0.8.
The API and capabilities of the latest release of InfluxDB are completely different from those of InfluxDB 0.8.x, which is why Grafana handles them as different data sources.
For more information, refer to Using InfluxDB in Grafana.