In German language this is called a "Wender", from wenden = to turn.
These were actually quite common in flintlock times and I see no specific link to Bohemia or Lebeda, except he still used the Wender principle for his 4-barreled guns.
My feeling is that in percussion times the double-barreled "Wender" was phased out and the true double or cape gun (mostly side by side) took over - but this is just gut feeling.

Here is another example:
http://www.hermann-historica.de/db2_de/aktuelle-auktion.html

Regards,
fuhrmann

Last edited by fuhrmann; 02/14/13 05:11 PM.