Display details on Map View / Widget

I have a list of locations that I’m displaying on a map.
In the map view, if I click on a marker, I can see the item name.

However, when I have more than one item that shares a location / address, clicking on a map marker only results in displaying a single item rather than all of them.

I’d like to be able to display all of the items that share a given location.

The use case is to be able to view a list of assets or people in a location when selecting it on the map.
The number of items that may be in the same location may be a maximum of 12.

Any ideas on how I can achieve this?