Multiple marker not visible popup

Hi, when I add more than one marker, just the last one show me the popup but alla marker are “visible” like this:

[leaflet-map lat=45.73268291512807 lng=11.552124023437502 zoom=7]
[leaflet-marker visible lat=45.44086267178177 lng=12.376098632812502]Venice[/leaflet-marker]
[leaflet-marker visible lat=45.452424241343124 lng=9.184570312500002]Milan[/leaflet-marker]

Only “Milan” show me popup, and “Venice” show popup only when cliked.
there is a way to show all popups open?
Thanks, Andrew