initial sync of multiple streaming slaves simultaneously

    We currently have a 9.1.5 postgres cluster running using streaming replication.  We have 3 nodes right now

2 - local that are setup with pacemaker for a HA master/slave set failover cluster

1 - remote as a DR.

Currently we're syncing with the pretty standard routine

clear local datadir

pg_start_backup

sync datadir with fast-archiver (https://github.com/replicon/fast-archiver)

pg_stop_backup 

start slave

We use the streaming replication with wal_keep_segments set to 1000 to get the required WAL files to the slaves.

With this procedure we can currently only sync one of the slaves at a time if we failover.  As when the second machine goes to start the sync it errors out cause trying to run pg_start_backup fails.

We're looking into was to allow both the slave and the DR to sync at the same time.

The procedure I'm currently testing is 

clear localdatadir

pg_start_backup

scp datadir/backuplabel

pg_stop_backup

sync datadir with fast-archiver

start slave

This seems to be working and the slave comes up correctly and streams the WAL files it needs from the backup_label that was copied during the pg_start_backup/pg_stop_backup

Is there any hidden issue with this that we haven't seen.  Or does anyone have suggestions as to an alternate procedure that will allow 2 slaves to sync concurrently.

Thanks