Strange behaviour of mongoimport: it imports less documents than expected

[bitliner]

I am running end to end test on a web app.

So before each test I make tokumx empty and then I load some collections with mongoimport.

I launch multiple mongoimport commands in parallel.

The result is that it imports only 600 documents insteaf of 800 documents as expected.

then if I make the that collection empty, and I run again manually - after the test - mongoimport command only on that collection again, still it imports 600 documents instead of 800 documents.

To make it work well, I have to run db.dropDatabase() or db.collectionName.drop(), so if I run again mongoimport now it works normally importing the whole set of 800 documents instead of only 600.