Hello,
On the attached document I created two different polylines, in red (colour changed afterwards), and then tried to replicate them with the "Create Equidistant Polylines", various Spacings but only 1 Copy.
The arc, drawn with the Angle option, will not accept a replicate on the inside.
The other one, Tangential, ends up replicating only as a line outside and inside.
Here is the file:
Strange_Polylines.dxf.
OS is Windows 10 and LC is revision 2.0.9-49-gff1149e.
As you can see I improved my Polyline skill.
Regards,
Christian