Ok, I did make a mistake during DXF export of selecting two views of my shape (one was a orthogonal view and the other was a plane dissection, which happened to be one and the same set of lines) to export which duplicated all lines. However, I recall that I did this in the past and instead of the result in 0.9.8N, I got a chained result (may of had two polylines but I can't recall.)
Anyhow, I exploded the shape and got rid of the line duplicates and rejoined the group and got the expected result.
While I did not mean to output two copies of the same arcs and lines, I would have expected "join" to simplify duplicated lines/arcs to one single line, then join the ends that are within the tolerance. The first pass of the join algorithm could look for line duplicates, delete one, then join the ends that are within tolerance.
Anyhow, while this simple shape was easy to fix, a different, more complex shape with one or more "accidental" line duplications (i.e. somehow drawn over each other twice) could take significant time and effort to debug and fix in cambam. If the "join" algorithm first simplified the drawing by removing duplicates and then join the segments within tolerance, it would prevent the output I observed and make it easier on the user.
