Importing via xml deletes already populated fields???

[Leeckly]

Hey all

Im kind of new to this, so any help would be great.

I've created some forms that have similar named fields but some fields are named differently, If I fill in one form and export data as xml and then import this data into another form that has has a few textfields/numericfields already containing data, the imported data imports fine, but the the fields containing data previously, which have totally different field names are wiped?

Anybody have any ideas at all?  All information would be superb.

Lee