Why does the importer say items already exist?

If I create a brand new wordpress instance and import an export file from wordpress.com, why do I get a lot of messages like:

Media “LG Optimus Bright L-07C first impressions” already exists.
Media “LG Optimus Bright L-07C first impressions” already exists.
Media “LG Optimus Bright L-07C first impressions” already exists.
Media “LG Optimus Bright L-07C first impressions” already exists.
Media “Fukushima No. 1 nuclear plant tour for reporters – radiation dangers temper sense of stability at scene of devastation” already exists.
Media “Some hanami photos April from my better-than-iPhone camera” already exists.
Media “Hao and Mon this evening” already exists.
Media “Hao & Mon go to the vet to get their nails clipped” already exists.
Media “Fukushima village on way to becoming ghost town | The Japan Times” already exists.
Media “Reactor 1 in worse shape than thought | The Japan Times” already exists.
Media “Hao & Mon go to the vet to get their nails clipped” already exists.
Media “My Neighbor’s 40 year old turtles” already exists.
Media “Hao-chan playing in my shirt” already exists.
Media “All sealed up against come what may” already exists.

This is a brand new, just created wordpress instance.

Also, the importer keeps on timing out so I restart it 4 or 5 times until it’s done. I can’ think of anything else to do…

Thanks,

doug