Can anyone help?

If I have a column of 10 digit numbers, is there a function which can
identify when a number is repeated

e.g.

A B
1 Number Repeat?
2 1234567890 Yes
3 2345678901 No
4 3456789012 No
5 1234567890 Yes
6 4567890123 No


So I need a function entered in column B which searches down the entire
column A to look for an identical number and if it finds one, it puts in
"Yes" and if not it puts in "No"

Thanks

John