In the Bitcoin App (Chrome) you are also able to create several accounts. So, for your use case you do not have to buy a 2nd Ledger.
Mentioned here:
https://www.ledgerwallet.com/apps/bitcoinMULTI-ACCOUNT
All your BIP 44 Bitcoin accounts are managed within a unique interface, where you can send and receive, on-demand, in real-time.
But I like the idea of using two Nanos as they will be less used, less likely for hardware failure, and two different pins, and set ups, and seeds.
And I will spread the risk if something goes wrong with one of them, losing the seed, etc...
I wouldn't get a second ledger, you're just wasting money at that point. You might be interested in the
plausible deniability options the Nano S offers. You should have a paper backup of your seed on the card that came with it anyways, so you don't need another device just to store your seed again. Even if your device breaks, if you still have the seed backed up (which you should), you can recover your funds without buying another device by importing it into a supporting wallet
(source).
I have a seed card, but I don't want to store all my coins in one account with one seed. I want to spread out the risk.