First of all I will never recommend to run two Antiviruses in a system because it will consume lots of your system resources. A single Antivirus always take 30 to 40 percent of resource during scanning and all those stuff.

Second running two antivirus may conflict during any operations which will leads to unnecessary notification and lagging of the system they will not be able to scan properly because if one Antivirus try to scan the system then other antivirus may think that some malicious software trying to entering into system.

Yah there are some Malaware scanner like Malwarebytes who does allow to run side by side with other antivirus because these are not a fully antivirus software. But only the free version of Malwarebytes allow to run side by side. Because free version does not have any real time scanner.

If you agree please do vote this will encourage me to keep answering these type of questions in future.

Thank you .