Hey there @oldmicky
There's no issues under Windows 10 and PC, ANA 1.5 and ANA 2 are 2 different plugins, you can have both of them running on Windows.
The only concern you might have is to be sure to use the correct installer depending of your OS & DAW specs and if you're working in a 32bit or 64bit environment.
So in this regard, you can't install both 32bit & 64bit version for the same plugin, that will cause issues. Now with latest ANA 2 v2.0.97, 32bit support is now over anyway, so if you're on a 64bit OS & DAW then you simply have to make sure to use the 64bit installer for ANA 1.5 since you won't have the choice for ANA 2 latest anyway.
Now since you're planning the install on a new PC, I suppose it's a 64bit OS and so will be the latest version of your DAW software, so just install ANA 2 v2.0.97 and make sure to run the 64bit installer for ANA 1.5 and you'll be fine.
Also keep in mind the "devices" limit for authorization, you can authorize the plugins up to 4 machines, so depending on your previous installations you might need to revoke older devices, you can do this form your My Account/My Devices area once logged onto the site.
That's the only bit that I can think about potential issues to run both plugins under Win 10, the real issue is for Mac users since ANA 1.5 won't work above MacOS 10.14
Hope this helps