DS didn't support LB! This is the reason why clients are doing restarts when they are switching from one DS to another.
If I recall right in ideas.splunk.com there is already request to add LB support to DS. But before that you must remove that LB configuration and use only one DS server. Of course you could do warm standby server (splunkd down) where you automatically replicate (e.g with rsync) configurations from your primary DS and if/when needed just bring that warm up with correct IP, GUID etc.