Fatal error after starting postgres : sys identifiers must be different

Hi Alvaro,

Could you please let me know what does the error "system identifiers are
same" mean? Below is the snapshot from one of the masters.
I am setting up BDR as per the wiki
http://wiki.postgresql.org/wiki/BDR_User_Guide#Initial_setup
and source @
git://git.postgresql.org/git/users/andresfreund/postgres.git

irc1(at)ubuntuirc:~/bdr2/postgres-d6ed89e/postgres-bdr-bin/bin$ ./postgres -D
~/bdr2/postgres-d6ed89e/postgres-bdr-bin/bin/data2/
LOG: bgworkers, connection: dbname=testdb2
LOG: option: dbname, val: testdb2
LOG: registering background worker: bdr apply: ubuntuirc2
LOG: loaded library "bdr"
LOG: database system was shut down at 2013-03-17 10:56:52 PDT
LOG: doing logical startup from 0/17B6410
LOG: starting up replication identifier with ckpt at 0/17B6410
LOG: autovacuum launcher started
LOG: starting background worker process "bdr apply: ubuntuirc2"
LOG: database system is ready to accept connections
LOG: bdr apply: ubuntuirc2 initialized on testdb2, remote dbname=testdb2
replication=true fallback_application_name=bdr
FATAL: system identifiers must differ between the nodes
DETAIL: Both system identifiers are 5856368744762683487.
LOG: worker process: bdr apply: ubuntuirc2 (PID 16712) exited with exit
code 1
^CLOG: received fast shutdown request
LOG: aborting any active transactions
LOG: autovacuum launcher shutting down
LOG: shutting down

Thanks.