I run tables through Access, do a round to a suitable resolution for coordinates, append duplicate coordinates as addition records and theme as a piechart (all in queries and append functions). Only real problem is you need to know the max number of duplicate points that will occur so you can set up a final table with enough fields. This can probably be done programatically as well, but I was happy enough to have a solution. This lets you show something meaningful on a map, but keep the real data. In this case you would need to create a few tables for different resolutions and put them all in the display with different scales set for visibility of each.