After setting a layer's labeling properties to not show overlapping labels, sometimes the overlapping labels are still displayed.
There are several scenarios for which this may occur:
· You are using a conflict detection buffer tolerance.
· You are using a text symbol with a halo mask.
· You are projecting the map such that it is wrapped around the horizon (example, customized World Robinson).
If possible, avoid the mentioned scenarios, or convert the labels to annotation and edit their position.