Can the 2 versions co-exist on the same server like 10.1.400 and 10.1.500 could?
it seems either installer wipes out the data manager extensions version folder 
while I can run both versions, I can not import a data fix for the older version because the data manger extension is not there (or registered)
Somehow I got them both installed now
I was thinking about doing the same; did you have to do anything special to get it to work for you?
I think I messed up when I installed 10.2 and did not install the components for prev version. Somehow in my fiddling around I managed to get the database server manager to run again and I installed the components