Another thing worth noting here is that delegation is a per-wallet, more specifically per wallet key phrase thing. That’s why Jane doesn’t pay any fees to delegate again to the same pool. In fact, because it’s a per wallet thing, the 2000 ADA added to a wallet already delegated automatically get delegated as well. There is no additional step to take and this happens always.
In the future, Cardano will support multi-pool delegation from the same wallet so you could then technically stake with more than one pool from the same wallet. Today, if you wanted that option you’d have to split those funds between separate wallets and delegate each wallet to a different pool of your choice.
Also worth noting, the 2 ADA delegation fee is refundable if you ever chose to stop delegating entirely., I.e, sell all your ADA for example. (Currently undelegate feature only supported in Yoroi) but protocol certainly supports this so most wallets should support this in due time.
Finally, delegation is per wallet key phrase so the fact you delegated using the Yoroi wallet doesn’t mean anything would change if you happened to recover your key phrase using Daedalus for example. You’ll see what the blockchain sees about your wallet and that it is delegated just as you’d expect. Daedalus and Yoroi are just 2 ways you can see and manage your wallets on the blockchain.
Have fun staking.