How to configure MySQL Router on two application servers?

I have three MySQL servers running with group replication and inside a InnoDB Cluster. I have two app servers that will be connecting to the cluster and I need to configure mysql router on both app servers. When I run router on server1 I use the --bootstrap option. When I try to do it on server2 with --bootstrap I get an error >a router instance named has been previously configured on this host. My question is do I need to start mysql router with --bootstrap option? Or since it will be configured on two servers --bootstrap option is not required? Do I need to start mysql router with a personalized conf file?