Yes, some Merkels circa early 2000’s will double when firing the rear barrel first. Mine does. It is a 140AE in 9.3x74R. From what I’ve found researching the Internet, there is an internal design fault which can be repaired. I never bothered, but I also don’t use mine for DG hunting where I might select one barrel over another, ie, pick a solid over a soft. In Canada, it is EXTREMELY difficult to have any manufacturer work done because warrantee centres are all but non existent (and pretty useless and slow when they do exist), so most warrantee work involves shipping cross border/international, with all manner of hassles, and permits required.