How do I enter multiple cash flow entries for the same date?

You cannot have 2 cash flow entries for the same date. It's a technical limitation.

You have to either and make one cash entry with the total value of all the transactions happened on that day. You can enter the details of the transactions as Notes.

Keep them as separate entries but you have to enter adjacent dates. E.g., if the first entry was for 10 Jan, enter the next for 11 Jan and then 12 Jan etc.