TotalFetchRequestsPerSec not equal to sum of Fetch and FetchFollower Request Rate

TotalFetchRequestsPerSec: kafka.server:type=BrokerTopicMetrics, name=TotalFetchRequestsPerSec

Fetch: kafka.network:type=RequestMetrics, name=RequestsPerSec, request=Fetch
FetchFollower: kafka.network:type=RequestMetrics, name=RequestsPerSec, request=FetchFollower

I found a big difference between TotalFetchRequestsPerSec and sum of Fetch and FetchFollower Request Rate. 
I don't know why topic-[2-10] has no Byte in/Out, but metric tell that TotalFetchRequestsPerSec of topic-[2-10] >0.

TotalFetchRequestsPerSec for all topic:

broker fetch and fetchFollower rate:

This is easy to reproduce, TotalFetchRequestsPerSec always more than sum of Fetch and FetchFollower rate.