Q: Can I have two anti-virus software apps in my computer?
A: If you are using antivirus software that is operating in real-time scanning mode, then when you open a file, or download an email, the antivirus scans it then.
If you have two such programs installed, it is possible they will each want to scan the file before the other - they are designed to scan files before they are seen by anything else - including another antivirus app. This is where conflicts can come in.
The other issue is that antivirus software takes memory and cpu resources. Having two (or more) simply increases the needed resources, which are now not available for other applications.
Of the 40,000,000+ malware in existence, the quality, independently-test antivirus software will catch 99+%. How much more will having 2 programs catch? Most likely none.
Lastly, application whitelisting is the currently recommended standard to prevent malware from impacting your computer, and yet virtually nobody does this. Technically, you do not need antivirus if application whitelisting is in effect (and not bypassed by the user).
Which is all a long-winded way of saying yes, you can have two anti-virus software apps in your laptop, but there is not a single valid reason to do so, and many valid reasons to not do so.