Beovox 1600 are quite rare but wonderful panel speakers.
It's correct that two versions were produced, but both versions are two-way.
Type 6219 (mk1) has a Peerless cone tweeter and Heco woofer
Type 6228 (mk2) has a Philips dome tweeter and Celestion woofer.
The Beovox 1200 (not 1600) was available in no less than three different versions, both
two-way and three-way. The earliest version of Beovox 1200 had the exact same drivers
as the Beovox 1600 (mk1), only in a thicker box cabinet.
Maybe this is what you read about.
The "Series 2" is a production "batch" number, not always referring to a
change in the actual product.
Some Beovox 1600 have the neat metal B&O logo on the front while others have a square
silver plastic batch with black lettering.
Worth restoring and we like photos.
Martin