Help!

I did an import last night into my nation to update some data that had been incorrectly imported originally. When I did the import, I added a tag so that I could identify who had been updated.

However, this did not add this tag to my people -- it overwrote the existing tags!!! We had large amounts of invaluable data that we need back contained in the tags attached to each person. I cannot understand why tags were overwritten when the part of the import form is clearly labelled "Add tags to each person". What part of "Add tags to each person" would suggest that adding a tag deletes old ones?

As you can imagine, I am somewhat panicked. I did these two imports last night. How can I restore my previous tags to my data?

Please help.