When I copy a clip from the EX1 to an HDD on the PC using Copy/Paste in the Sony Clip Browser I end up with 4 copies of the clip rather than the 1 copy I was expecting. Why is this ? Should I just delete 3 of the 4 copies and forget it ?

Are you certain that you have 4 identical copies?

Yes, absolutely. ***01, ***02, ***03 and ***04.

What is the duration of the clip? There is a 4GB limit on a FAT32 formatted cards, about 13 min. long, so, if the clip is longer than 13 min. you'll get multiple chunks 01, 02, etc... This is normal, place them on a timeline butt to butt...

The clip is 50 mins long. The whole 50 mins clip is copied 4 times. The 4 copies are identical.

Do a non clip browser copy and paste to see if the same thing happens. Turn on CRC checking if that's not on.

I am 99.99% positive you are seeing this in a NLE, maybe Premiere Pro because I see the exact same thing with my EX3's clips, but oddly, not my EX1. You only need to import the "01" file.

To summarize, this is completely NORMAL.

EDIT: well, duh to me. I just saw your info which says Premiere CS5 which is what I use.

No problem - of this kind - with importing without using the Clip browser, Jack.
Thanks Steve for reassuring me that this is nornal - funny kind of normal, but there you go !