Can you - yes. Should you - it depends.
Everything you install on your Windows based system take up resources. Everything that runs on your system, either actively or in the background, also take up system resources.
The CPU, memory, and hard drive space on your device are commodities and they have physical limitations.
All of this comes into play when answering the question about having multiple anti-virus/malware scanners installed on your device.
First - you should have at least one anti-virus/malware scanner on your system that performs real time scanning of files, downloads, and other activity on your device to prevent any infections from occurring. For me that means Windows Defender on Windows 10 and before that its predecessor Microsoft Security Essentials. That protection and good computing habits has kept my devices infection free for many years.
Installing a second real-time scanner on your system may be possible because the system is not going to stop you from installing software if you have the right permissions however, it is not always advisable.
The reason for this is two fold. First you are using more resources than just keeping one active scanner installed and running. This will eat into the finite amount of CPU, memory, and storage resources you have on that device. Second, you will likely experience slow downs on the system as each individual scanning process that is active attempts to scan the same files or processes as you use your computer. This of course will make it seem like your system is slower than normal because it is doing twice the work. Then there is the possible conflicts as one scanner tries to scan the same file being scanned by another real-time anti-virus/malware scanner. It can get very messy indeed.
A yes answer to this question becomes possible when you consider installing an on-demand scanner on your device. They key difference between this and a real-time scanner is that the on-demand scanner only uses CPU and memory resources when it is actively scanning your system upon your request. The storage space it takes up is likely of little impact unless your hard drive is nearly full.
Installing an on-demand scanner would allow you to scan for unique threats however, most real-time scanners have options for executing either manual or scheduled scans across your entire system. This can be very handy when you would like the warm fuzzy from a 100% scan of every file on your hard drive done on a Saturday night when you are not using your system.
The choice of security scanning software is very personal so I am not here to recommend one program over another. Always use what has proven to be most effective for your protection. Combine that with good computing habits such as not clicking on unknown/unexpected attachments, obscured URLs in an email, or links/ads on questionable websites and you should be well protected.
When all else fails, and it can happen to the best of us, make sure you have a back up system in place to protect your important files and software.
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