Time Machine restore dumped backup on top of existing system

After a complete HD failure resulting in the loss of 75% of my final year university work, I decided to set my external HD up (which was a media library) with Time Machine. Why oh why hadn't I done it beforehand one says, ah the joys of hindsight...

Well anyways. A couple of weeks or so ago I downloaded the discography of Lil Wayne, which accumulated a good few gigs of content. I dragged it all into my iTunes library only to see it bring up 1000's of incorrectly spelt & poorly punctuated song titles, which as the owner of a pedantic library found this quite a horror show. Without knowing what I know now and not thinking it able to delete songs directly from the 'Recently Added' playlist, I thought the best thing to do would be to restore the entire system from the latest backup, which was about an hour before I did the whole thing.

So I enter Time Machine, and after realising it is one of those terrible Front Row-esque interfaces, I click restore on the most recent backup. This is what happened:

- It took a good half an hour to do the restore.
- When complete, I went into iTunes to see that the songs, all thousand or so of them were still there, incorrectly titled, exactly as they had been just before I decided to restore!
- Nothing much seem to have changed, I'm sure looking back the trash can was the same, even though I knew for sure it should have changed due to me moving files around since the backup which I restored from (may be wrong on this one....)

So instead I learned you could delete straight from the 'Recently Added' playlist, and I forgot about the whole thing. This was until yesterday evening when I noticed by chance I had little or no room left on my HD.

After downloading Disk Inventory X and having a search I see this:



1. Turns out the Lil Wayne discography is there with a Belle & Sebastian one too, even though both were long deleted. Navigating to where it says they are located provides no fruit, until I locate them in finder and see this:



Looks like Time Machine just dumped my restore next to the current system I was operating. Why the hell would it do this? I take it I'm ok to just go ahead and delete the old one?

Also the 2. in the bottom right. Its path is /private/var/vm/sleepimage, and it's over 4GB. What is it?

Help and explanations would be greatly appreciated. I'd like to utilise Time Machine and use it to my advantage but this isn't selling me whatsoever.