In many cases you can use two for real-time protection but you will be using up quite a bit of extra system resources running two which will likely impact the user experience noticeable and secondly they may fight over quarantine of threats or in some cases may quarantine each others components. If you want something that can act as a stand alone scanner I would simply use a tool that is designed for that purpose such as the free version of malware bytes or Spybot.
My honest opinion is if something breached your real time protection in many cases the damage is already done such as malware that is considered info stealing, acting as a botnet, and ransomware to name a few.
IMHO you should be more interested in adding layered defenses vs two the same security tool type. This is referred to as defense in depth.
Having tools like
Endpoint protection (media usually just refers to as anti-virus)
Firewall (either host based or at your network perimeter)
Leverage a DNS service that helps protect against spam/phishing and malware (there are free services that you simply need to point your router at for your DNS forwarders)
Use a password manager and have unique passwords per site/resource to help protect you from credential stuffing and data breaches
Backing up your data to protect against ransomware
This list could go on and on but these are some of the easier/cost effective things people can do at home
