David,

I just stumbled across another post, this time on Stummi, where the poster was commenting on the two destination boards per side on the Ep. III D-Zug set by Hobby Train that is the Ep III version of the Ep IV "Woerthersee" set from LS Models.  He writes that he looked into it and found that, strictly speaking, German coaches from that era should have a single destination board per side, located either in the middle of the coach or at the right end, except for in international (RIC) trains, which should have coaches with destination boards at both ends.  He then goes on to say there are photographically documented exceptions!

Hope this helps
Tom