Fixed $(VERSION.IF_MULTI)

Variable substitution actually errored out when duplicates were present.

lib/dtutils/string.lua

@@ -744,7 +744,7 @@ function dtutils_string.build_substitute_list(image, sequence, variable_string,
       string.match(image.exif_datetime_taken, "(%d+):(%d+):(%d+) (%d+):(%d+):(%d+)$")
   end
 
-  local version_multi = #image:get_group_members() > 1 and image.version or ""
+  local version_multi = #image:get_group_members() > 1 and image.duplicate_index or ""
 
   local replacements = {dtutils_string.get_basename(image.film.path),-- ROLL.NAME
                         image.path,                            -- FILE.FOLDER