Your code (I would hope that you plan to include a by statement so that it sorts by one or more variables) won't alter ref.dname.
It will simply create a file called work.dname2 that looks like it the original, but sorted in whatever order you specify,
The only way I can think of where it would actually alter a file is if one used the old style macro code to rename work.dname2 to be referenced as ref.dname. But, unless someone was really mischievousness (and old enough to know about old style macros), I can't imagine that happening.