It is idea that Ledger is promoting for some time, and I do not see anything wrong in that, except for the fact that for some people is too expensive to buy one hardware wallet, two is just to much.
What promotion are you talking about? I'm quite confused about what you're saying. Did ledger promote having two wallets?
You shouldn't be confused with my post since you post link to back pack bundle in your post :
and they say about it :
This pack contains a Ledger Nano X and a Ledger Nano S to always keep your assets available and out of harms way.
Securely manage your assets on-the-go from your smartphone with the Ledger Nano X, and keep the Ledger Nano S for at-home use or in a safe storage as a backup device.
Regarding some discount form Ledger, why not save some money if they offers something like this every year. But maybe we can save even some
BTC if price is go up in next months, it is not same if you pay 0.015 or 0.01 for same device.