Elasticsearch additional node

In our local network I have some server with Logstash + ES + Kibana to analyse the logs from others servers, let's call it log-server.

Just for information, the others servers send the logs using rsyslog facility to the log-server, so logstash get files from /var/remote-log/ directory and then passing them to ES and then to Kibana.

Recently the servers starts to work wrong... I don't know if it's the problem, but...
Some minutes after the start we see another node with the same IP :

log-server:9200/_cluster/state/nodes?pretty

{
"cluster_name" : "LOG",
"nodes" : {
"ylTo0EIRQoeTRpmeFbuKkQ" : {
"name" : "<log-server_dns_name>-1849-14534",
"transport_address" : "inet[/:9301]",
"attributes" : {
"client" : "true",
"data" : "false"
}
},
"9a9iB_OHQYaUotDV-9fcQQ" : {
"name" : "Roland Barthes",
"transport_address" : "inet[/:9300]",
"attributes" : { }
}
}
}

In the ES config there are only two uncommented lines :

cluster.name: LOG
node.name: "Roland Barthes"

All others lines are commented.

So I don't understand where the node "<log-server_dns_name>-1849-14534" comes from?
And that I should do with ?

Just for information. In the same local network there are another ES server, but the "transport_address" of my second node is the same as the log-server's one... so I do not think that there is some link with another ES- server.

logstash version : 1.5
ES version : 1.6
Kibana : 4.0

Thank you for your help.

The other node is probably Logstash connecting with the node protocol.

Is it something new?
Because I'm pretty sure that before there was not this additional node...