If the answer is yes, where can one find the support document or article detailing such conflict?
VSE = Virus Scan Enterprise
You posted in the Consumer section, and I can't advise you about any conflict involving the Enterprise product. The question has been moved to Business / Endpoint Security / VirusScan Enterprise for attention.
Generally, you should not, and possibly cannot, run two virus scanners simultaneously.
Yes Microsoft Security Essentials contains antivirus so should not be used at all if you have a 3rd party antivirus such as McAfee, whether Enterprise or Consumer versions. You can run Windows Defender, however, but only in XP (an optional download), Vista or Windows 7 (already installed) but not in Windows 8 as that last OS includes an antivirus in its version of Windows Defender.
Running 2 antivirus engines can clash and actually leave you open to infection.
This is not in any particular support documents, it is and always has been a basic part of Windows knowledge, the same knowledge that tells us to never run two software firewalls together, but 1 software firewall and 1 hardware firewall, as in a router, is fine.
I am aware of such knowledge but was looking for an official acknowledgement from McAfee.
Nevertheless, all of your responses are greatly appreciated.
On page 10 of this document http://www.sfsu.edu/~helpdesk/vscan88/vse_880_installation_guide_en-us.pdf it states:
CAUTION: You must uninstall any other anti-malware products before installing VirusScan
Enterprise. McAfee does not support installation with other third-party anti-virus solutions.
OK that's an external guide but I am sure the FAQ's in the portal have a similar instance which a search would find.
I help on the consumer side only so am not familiar with that side at all, sorry.
Edit: Also see the Summary on this page: https://mysupport.mcafee.com/eservice/templatepage.aspx?sURL=3&pl=0