I don't know where this is being referenced, however, even after I deleted the /opt/splunk directory which contained version 5.0.1, I continue to get a barf and have no idea where this is being defined.
conflicts with file from package splunk-5.0.1-143156.x86_64
file /opt/splunk/share/splunk/search_mrsparkle/templates/searchhelper/snippet.html from install of splunk-6.0-182037.x86_64 conflicts with file from package splunk-5.0.1-143156.x86_64
file /opt/splunk/share/splunk/search_mrsparkle/templates/summarization/summary_details.html from install of splunk-6.0-182037.x86_64 conflicts with file from package splunk-5.0.1-143156.x86_64
file /opt/splunk/share/splunk/search_mrsparkle/templates/top/info.html from install of splunk-6.0-182037.x86_64 conflicts with file from package splunk-5.0.1-143156.x86_64
file /opt/splunk/share/splunk/search_mrsparkle/templates/view/app_setup.html from install of splunk-6.0-182037.x86_64 conflicts with file from package splunk-5.0.1-143156.x86_64
file /opt/splunk/share/splunk/search_mrsparkle/templates/viewmaster/create_dashboard.html from install of splunk-6.0-182037.x86_64 conflicts with file from package splunk-5.0.1-143156.x86_64
file /opt/splunk/share/splunk/search_mrsparkle/templates/viewmaster/edit_dashboard.html from install of splunk-6.0-182037.x86_64 conflicts with file from package splunk-5.0.1-143156.x86_64
get rid of the previous packages
yum remove splunk-*
Those sound like conflicts reported by your package manager. Debian? RPM?