Answer: false. They are different structures, not two names for one join. A double surgeon’s join is a doubled overhand knot: both lines are held together, an overhand knot is formed with the doubled pair, and the pair is passed through the loop a second time. A double fisherman’s knot is two separate strangle knots, one tied on each line around the other line’s standing part, then drawn together.

The names are tying instructions. “Double surgeon’s” tells you to double the lines and pass the whole bundle through twice — the “double” belongs to the overhand, not to a second knot. “Double fisherman’s” tells you to tie a knot on each line and let the two jam against each other. If a source says double surgeon’s and you tie a double fisherman’s, you have not tied the join it asked for.

On the water, that difference decides what you are tying. A leader formula that calls for a double surgeon’s join between a leader and a lighter tippet is asking for the fast doubled-overhand join, not a two-knot bend. The surgeon’s join earns that place because it is easy to tie and handles moderately unequal diameters; it is also bulkier than a blood knot and can leave a slight angle. Know which of the two you are tying, and why.

Source

From the Surgeon’s Join knot page; the written exam’s knots material is in the CI Study Guide (2025); terms follow the FFI Fly Casting Definitions.