Make a copy of your ResViewer folder and rename it to ResViewer2,
also start each ResViewer.exe from his own folder.
The temporary files written and read during navigation are then stored at different places and will not disturb the application.
For more security make change to only one resource file and use the second just as a reference.
When you look at the temporary folder you will see that each selected item or sub item is written there.
If you open a plane resource the first file will be the plane palette, this is used all the time.
If you open 2 differen plane within the same folder there will be conficts using wrong files or with locked files !
All files inside the temp folder are deleted at termination of ResViewer