Unsure if DGN files in your folder are V8 or Microstation J?
From Eric Bridwell – BWSC
In V8 Microstation Manager, before opening a dgn file,
the ‘Show File Icons’ can be selected to show which
Dgn files are V8 and those that are Microstation J.
V8 files will have V8 Icon.
Microstation J files will have the Bentley Logo Icon.