My sony ereader has synced my books a multiple of times so I now have approx 12 copies of each book on my ereader. Is there someway to stop this or have I done something wrong?

I am not sure how you have managed to do this I have not had this problem with my sony.

Just delete the duplicates off your Sony eReader.

Also I just use Cailbre to 'manage' my library rather then the Sony Software. It was actually recommended to me by the guys at the Sony Store when I purchased my eReader.

Mine does this too, it seems to be a flaw with the Sony Reader software. I have turned off syncing and drag and drop now. It is apparently a fairly common problem.

IsolaBella, do you need to strip the DRM from purchased EPUBs to use Calibre instead?

No you don't strip the DRM from the epubs to use Calibre.

I actually download the books to Sony Software, put on eReader then take off eReader and put on Calibre to index them (most of mine are series and I label and number the series), then I re-import them to the eReader.

I can 'read' the book online on the Sony Software BUT I can't open the book to read from Calibre due to DRM BUT it still passes back to the Sony reader fully intact and able to be read.

ETA: I think I have avoided the problem as I don't 'sync' and just drag and drop.

Thanks, I'll give Calibre a go. Sony make great products but sadly their associated software is usually lacking!