You can run two websites on the same account. Although it's generally cleaner to have two different accounts.
If you run it on the same account, you can add an email address for each. And then when you send a broadcast email, just make sure you are using the email address for the relevant website. Same with sequences.
A couple of downsides to running it on the same account:
- If someone unsubscribes, they'll unsubscribe from both
- Tags can get messy, depending on how many you have
- The default email address is one email address, so you'd need to change that for every sequence and broadcast
ConvertKit recommend that if audience is different, then use different accounts. If the audience is the same, then one account is probably fine. More on that here: https://help.convertkit.com/en/articles/2502514-can-i-use-one-convertkit-account-for-multiple-domains-or-businesses171