I'm not exactly sure of the intent of the question Ian.
if you're asking how do you backup images to a memory card .. I think WA's point is that you don't backup to the memory card .. you leave them on the memory card!
That is, if you know that you're on holidays for A days, and you shoot B Gb's worth of images per day .. then you get C(where AxB=C) worth of memory card capacity.
eg. I tend to have about 2 - 3days off in any given instance. I shoot between 4-8Gigs worth of photos per day... at most, for the 3 days I may be out and about I therefore need 8(gig)x3(days) 24 gigabytes of Memory in terms of card space.
What I have tho is 2x 32Gig cards, a few 8Gig cards and a few 4Gig cards.
All images stay on the cards till I get home where I then transfer to PC.
This could be considered 'cumbersome' if you're on an overseas holiday for 2 months or so .. but the reality is that you're not really going to be shooting 100Gig's worth of (keeper) images per day every day for 60 days!
if you do, then they are almost certainly going to be multiples of a single scene, or snapshots .. or both.
Of course you're not going to rush out and acquire 100 128Gig memory cards for that purpose .. so the best course of action is to be ruthless with your culling process.
Do you really want to keep 6Tb's of snaps, or multiple images of the same thing?
ps. if the question is actually more along the lines of technical assistance ...
Many Android mobile devices exist where you can connect a card reader(or more) to the device and transfer images from one card to another.
You would need to be weary of the use of such devices and the onboard memory capacity of the mobile device in some situations .. but it can be easily and quite cheaply done(approx $200ish).