You can remove leading, trailing, and extra spaces between characters and numbers in Excel using TRIM(), SUBSTITUTE() or Find and Replace.

Removing these leading spaces – or trailing spaces that fall at the end of a cell's contents – requires an Excel function.

Open your spreadsheet in Microsoft Excel 2003 and double-click the cell in which you want the textual white space to appear. Press the "Spacebar" to enter single-character spaces.

Look for extra spaces in your values' cells. If your duplicate values have extra spaces in their cells, those spaces will also cause the Remove Duplicates tool to consider them to be unique values.