prevent polygons & markers from showing up more than once at a time
prevent polygons & markers from showing up more than once at a time

dainst/gazetteer,codarchlab/gazetteer,codarchlab/gazetteer,dainst/gazetteer,dainst/gazetteer,codarchlab/gazetteer,dainst/gazetteer,codarchlab/gazetteer,dainst/gazetteer,dainst/gazetteer,codarchlab/gazetteer