As DaveUK says Gecado was a tradename of GC Dornheim, Suhl, Germany.
I have a 20 bore, Gecado, side by side sidelock and bears the inscription 'Made in Spain' so I am now thinking that it may not be the same company or have been taken over by Dornheim at some time. There is a "U.S." stamp on a number of places so I am not sure if it has been in the US at some time.
If I can find any more about the company I shall post it and perhaps you can let me know if you hear any more.
Regards