How to open two independent instances of Foxit Reader?
There's an option in Foxit Reader's settings that allows multiple instances of the program to be opened.
Go to Tools->Preferences->Documents->Allow Multiple Instances
However in Foxit Reader version 7.2.2: go to Edit->Preferences->Documents->Allow Multiple Instances.
This will open single file in multiple windows not in multiple tabs. Then arrange windows vertically or horizontally to view two files simultaneously. However, I have not found the split window command like Adobe Reader in Foxit.
In Foxit Reader 6.0 this option is here:
File->Preferences->Documents->Allow Multiple Instances
In the others versions the useful funcations can be found here:
Edit->Preferences->Documents->Allow Multiple Instances