I have cells A1 through J1 populated with dates (some are the same dates, and
some are different).

* In cell K1 I'd like to write a formula which tells me if the value in
cell A1 is unique compared to all the dates in the A1-J1 range.

* In cell L1 I'd like to write a formula which tells me if the value in
cell B1 is unique compared to all the dates in the A1-J1 range

repeat for 10 cells.

What formula can I use to accomplish this?

Thanks in advance.