MapAList does not currently allow for consolidation of already created maps. Your best bet is to import into Google Earth which can handle far more pins than Google Maps.
Alternatively, you could put all of your records into a single Google Spreadsheet, add a column to your spreadsheet to differentiate records by type, and then use basic grouping to show the differentiation on the the single map you create. Step by step instructions for basic grouping can be found at:
http://mapalist.blogspot.com/2008/12/basic-grouping-to-show-differentiation.html