Before I started hunting upland I used to fish during the winter at Lake Tutira. As I was often fishing blind, which I hated but was better than not fishing, I was very keen to make every take count. I was also pretty focused on landing every fish I hooked.
One of the most frustrating aspects of lake fishing blind was hooking and playing a fish, then losing it when the second fly in a two fly rig foul hooked the fish. The hook in the fishes mouth would come out, and often the fouled hook would come out too.
This happens far more often in lakes than it does in rivers. I am not sure exactly why this is, but I believe it is because without running water the fish fight differently.
There are many ways of dealing with this problem, two of which I prefer over others. The first is to ensure that a two fly rig is separated by leader longer than the likely length of a fish. For me this meant approximately 700mm with the trailing fly tied to the bend of the hook of the first fly.
The other advantage of having distance between two flies is the fish usually sees the bigger one first, and locks onto that. If it refuses it will not associate the second fly with the first, and will sometimes take the second fly.
The second simple technique that allows a shorter length between the flies but stops fish getting foul hooked by the second fly is to tie the dropper to the eye of the first fly. This means that second fly is not directly pulled into the fish when playing the fish, so they are far less likely to become foul hooked. I’ve used this method a little in recent years, but have not fished lakes enough to be completely confident with it.
The third option is to tie a knot to the leader with a long tag end for the first fly. This means the flies swim independent of each other. I am not that keen on this method because it adds another level of complexity to fishing, and I try to eliminate potential problems. Having only sight fished for years I do not think that I would have caught more fish with this set up, with the more important criteria for a take is to get the flies to the right level in the water before the fish sees them.