I have a general question about .PNG.DDS file names. Why is it .PNG.DDS and not simply .DDS for file names? Was this way in FSX and such.
I can only hazard a guess as a programmer who routinely writes tools that process files: it’s easier to append a new filetype extension to a complete filename when creating a derivative file than it is to carefully strip parts of the old filename out without accidentally creating a problem/conflict, such as if you have one texture source in .png and another in .jpg with the same base name.
And even if no conflicts ever occur in any downstream developer’s workflow, the simpler name prediction is just slightly easier to work with at every stage.
On the other hand, it wastes four bytes per filename reference. shrug 