Delete duplicate entities dialog box
The Delete Duplicate Entities dialog box allows you to delete duplicate entities and overlapping lines, arcs, and polylines, and unifies partly overlapping or contiguous ones.
                    - Entity properties to ignore
 - Comparison tolerance
 - Options
 - Duplicates
 
Entity properties to ignore
Selected properties are ignored when comparing duplicate or overlapping entities.
Comparison tolerance
Sets the tolerance for the comparison process. If set to 0 (zero), entities must match completely before being evaluated in the overkill process.
Options
Determines how special cases are handled.
- Maintain associative entities
 - Associative entities are not processed.
 
- Optimize segments within polylines
 - 
                            
Evaluates segments of selected polylines individually, duplicate vertices and segments are removed.
- Ignore polyline segment widths: ignores the Width property of overlapping polyline segments.
 - Don’t break polylines: polylines entities are kept intact.
 
 
- Join collinear entities that partially overlap
 - Unifies partially overlapping entities into a single entity.
 
- Join collinear entities when aligned end to end
 - Unifies collinear lines and polylines having coinciding endpoints into a single entity or segment.
 
Duplicates
Determines what to do with duplicates: either delete them or move them to a Duplicate Entities layer.