Generated metrics have duplicate labels

We are using Keycloak which generates metrics using the jBoss CLI: https://github.com/keycloak/keycloak-containers/blob/master/server/tools/statistics.sh

 We want to use Telegraf (with the Prometheus input plugin) to read the generated metrics. However, we get the following error:

Error in plugin: error reading metrics for http://localhost:9990/metrics: reading text format failed: text format parsing error in line 34: second HELP line for metric name "base_gc_total"

The base_gc_total metric appears twice for some reason. See the full metrics output in the attachment.