Help with Excel Import

[meg99]

using 2007. I receive an Excel file that contains the following
fields: Unique ID, Start, Finish

I need to update my project file. In my file I have a number field I
have titled GG UID. It contains the unique id numbers in the excel
file.

I have the import map set to merge data and update on Unique ID to GG
UID

Problem: When I import the file, one of the unique id fields gets
updated incorrectly:

Example:

After import, myfile GG UID 338 gets updated with 358 data and the GG
UID field is changed from 338 to 358 and the real 358 never gets
updated.

Anybody ever seen this before? Is there something I have overlooked
in the import?

Glen