Many people like the idea of having more than one antivirus product on their computer at the same time, but it’s actually a bad idea.
Antivirus programs search your system for
programs that are monitoring and sending information about your computer. And the other antivirus product will be doing just that. You end up with two (or more) antivirus products going to war, trying to disable and remove one another.
And when a virus is found, the multiple antivirus products may both detect it, but only one can remove it. This can lead to reports of viruses still being installed that are actually long gone.
Not to mention, because of the way they function, (scanning every file and process running on your computer and every connection to and from the internet) antivirus programs can slow your computer down. Running two or more of these programs which are battling with one another for control of your system will bring most computers to a standstill.