Why is it cutting every line twice? (Finding duplicate and stacked vectors)

Why this happens

1. Exact-duplicate vectors stacked invisibly on top of each other. This is extremely common in imported DXF/SVG files and after copy-paste accidents. The toolpath dutifully machines both.
2. Bitmap tracing produces double outlines by design. Tracing a drawn line creates its inner AND outer edge as two vectors, so "line art" traces cut everything twice.

The fix

1. Select All Duplicate Vectors: choose Edit > Selection > Select All Duplicate Vectors. It selects every visible vector that is an exact copy of another in shape and location, so visually they look like one vector. Delete them or move them to a new layer.
2. The dotted-selection test: click a vector once. A single selected vector displays dotted or dashed. If it still looks solid, a twin is stacked beneath it: select and delete the extra.
3. The node-drag test: enter node editing, drag a node aside. If a copy of the shape stays behind, you found the duplicate (Ctrl+Z to undo the drag, then delete the twin).
4. Run the Vector Validator (Drawing tab) to flag overlapping contours and intersections across the whole job at once.
5. For traced line drawings: keep one of the two outlines and delete the other set.

Pro tips

• Double-cutting is more than cosmetic: the second pass recuts the same path and can burn or chatter.
• Imported CAD files also love duplicate segments (short overlapping pieces along one line). The Validator's overlap check can help find those.