I wrote this up using the AvA terrain map but it happens for the sfma terrain map as well.
In this scenario, I quit the AvA arena and see the Melee tab, then quit there to the sign-in clipboard and if I go online again, I briefly see the AvA arena's terrain map on the clipboard before it clears to show the Melee arena tab.
If I quit to the first clipboard screen, 'Online' 'Offline Practice' Choose Terrain' etc then click Online Arenas, I briefly see the same AvA terrain in the clipboard before the login dialog.
So I'm seeing that terrain map twice, between the online option screen and the login, then between the login and seeing the Melee tab.