If you wanted to double check, you could do so like this.
First, sort the data so that it is in the order you said.
Then, put this formula in row 2 of a helper column (assumes your order #s are in Col A, starting on row 2)
This will put a 1 on the first record, and a zero on any duplicates (including multiple duplicates).
Copy this formula all the way down, then copy the whole column and paste special, values.
Then extract the duplicates, and do a Data, AutoFilter on what you've got left. You should have only 1s left over in your helper column, which you can then delete. If you've got any 0s, something's gone wrong . . .