In some cases a location can have different scopes. For instance, a building can be both a sight worth visiting and an accommodation. In a guide article it can be named in several lists, but it should have the same marker symbol or count and it should be displayed on a map once only.
I propose the use of an additional GeoJSON property which represents an marker-id. Markers with identical ids should be treated as identical. If different marker colors and/or marker symbols are specified, only the first (or last) definition should be used.
This task was mentioned at Community-Wishlist-Survey-2017 (https://meta.wikimedia.org/wiki/2017_Community_Wishlist_Survey/Miscellaneous/Kartographer_improvements), which got the No.1 out of 214 proposals.