If you have copied Knoppix 6.2.1 files to a partition on your HDD and you try to boot from a 6.2.1 USB key, it will somehow switch over to loading and mounting everything from the HDD copy.

Is there any way to disable this, to force Knoppix to boot from a particular partition, or from a particular KNOPPIX/ directory, when there are multiple versions lying around?

Can we have a KNOPPIX6.2.1 and KNOPPIX6.4.3 directories each containing the relevant Knoppix files in different partitions and choose which one to boot from a Grub menu.lst? I'm trying this right now and at the moment, 6.4.3 strangely seems to boot the 6.2.1 partition (I put on 6.2.1 first). It also takes very much longer when it does this, sticking for a while at a "Probing EDD..." prompt.