Android Question GMap.marker ... surprising display position

Hi,

In an app using Google Maps, when map_Ready is fired ...

I add a marker with :
myMarker=myMap.addmarker(lat, lng,"title")
no trouble at this time

but ...
if I have a map markersMap, and I do :
markerMap.put(myMarker, myMarker)
then
myMarker is displayed in the Gulf of Guinea !

A log of myMarker.position print the 'real' lat/lng used when addMarker
So just the display is wrong

bug ?

thanks in advance