After a network failure,both servers running keepalived become master.

When the network is reestablished, both keep the MASTER state.

What could be causing it?

Edited: Another information that might be relevant, each server has two NICs.

Here is the virtual instance configuration:

vrrp_instance VGAPP {
    interface eth0
    virtual_router_id 61
    state BACKUP
    nopreempt
    priority 50
    advert_int 3
    virtual_ipaddress {
        10.26.57.61/24
    }
    track_interface {
       eth0
    }
    track_script {
        jboss_check
        #tomcat_check
        #interface_check
        #interface_check02
    }
    notify_master "/opt/keepalived/scripts/set_state.sh MASTER"
    notify_backup "/opt/keepalived/scripts/set_state.sh BACKUP"
    notify_fault  "/opt/keepalived/scripts/set_state.sh FAULT"
    notify_stop   "/opt/keepalived/scripts/set_state.sh STOPPED"}