SDHC card backup device

I'm looking for a small, inexpensive device to copy the contents of one full-size (i.e., not micro) SDHC card to another. Has this been done with Arduino? If not, would it be possible? Difficult for a novice? I imagine it would require stacking two SD card shields, but the ones I've found specifically exclude SDHC.

Nice application for an Arduino!

If you find the shields they will be controlled by a SPI interface (need 4 pins) and you will need to modify one of them so the select line is different. Search for SPI for the details. Two different shield may be easier.

Do you want to implement a diskcopy (disklevel) or a recursive filecopy (can eat up all ram) ?

Be aware that with the speed of an Arduino - 4K per second copy speed (guess) - the copying of a 4GB card take 1.000.000 seconds. That is approx 11 days.

That all said, I think its far more practical to use a PC to copy SDcards.

Thank you for the reply. I didn't know about the copy speed limitation. I agree, very impractical.