Balances in an internal and external wallet for staking?

In Yoroi, I sent over a small amount and staked it. Then later I sent the rest of the amount and it was automatically staked. I looked in Yoroi and in Base INTERNAL I see my first balance under a generated address. And in Base EXTERNAL I see my second balance under another generated address. Why is it like this? In my dashboard the Total Delegated is correct, the sum of both. But, what’s the deal with internal and external, and what differentiates them? Thanks!

Check this explanation: