Is it okay to install two desktop wallets in one PC? I mean is there a security concerns if one does that? Or there will be no problem if I do that, two different wallet software in one desktop will work well separately on one PC?
As long as they're actually different, there's no problem.
For example, you should NEVER install both Bitcoin Core and Bitcoin ABC (Bitcoin Cash) in the same computer. Those are coded with the same path to the data directory.