Emsisoft alone is more than enough people use 3, 4 and sometimes even more complement to their computer security, this is paranoia, they are protecting themselves from a threat that will never come.
It´s a good idea. Nothing protects you 100%, and SecureAPlus is really light. Install it without offline antivirus and disable the engines of Emsisoft, Bitdefender and Clam.
I am actually using the config now. Emsisoft Anti-Malware, SecureAPlus (Emsisoft Engine Disabled), Zemana Anti Malware (Only with Identity Protection enabled, Realtime Protection Disabled. I use it for Anti-Keylogger.)
@Windows_Security see what I mean ? You can find this all over the internet and in any retail venue that sells security softs. At least 1/4 of MT and Wilders is comprised of this type of thing - in one form or another.