This will depend on what you plan to do. If the dictionary files are updated to the current version, but you don't change any definitions, then there is no issue using them with previous versions.
If you do change some definitions, it will depend on the fields that you change. For example, the ddf file has added a FLAGS$ field to the end of the iolist, and the dde file has added an ORIGINATOR$ and ELEMENTTIP$ field to the end of the iolist. If you update a file definition in the current version using these fields, then modify the file again in the old version, you may lose the values in these fields.