I tried to setup "master - 2 slaves" configuration by article on digitalocean (https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-on-postgresql-on-an-ubuntu-12-04-vps).
First slave successfully connected to master and works fine. Second slave cannot connect. From postgresql (second slave) log:
2015-11-02 11:17:35 MSK [14198-1] FATAL: could not connect to the primary server: FATAL: too many connections for role "rep"
From log of master server:
2015-11-02 11:17:32 MSK [18981-1] rep@[unknown] FATAL: too many connections for role "rep"
Every slave need different user?