Importing Library Problems

I am working on a 700GB library and today I attemted to import (add, not merge) an additional library of 400GB.

The library is stored on a 2TB hard drive on a Mac Pro 2 x 2.8 GHz Intel, Memory 10 GB, Mountain Lion OS.

It took 5 hours for the library to import and once it completed, aperture started crashing.

The weird thing is that the library's size, instead of advancing to 1.1TB as expected, it has reached 1.96TB! I haven't forced quit it yet as it's risen to 1.97TB, which make me think that it is possibly not crashing, but is still imputting data.

Has anyone encoutered a similar problem with importing a library? Why has the size sky-rocketed? Am I endagering the files if I eventually force quit it?

And finally, is close to 2TB library really pushing it? If it all works out in the end, should I be expecting problems?

Thank you for you help

Eleni