In a full sheet range, I need a cell to be highlighted when a duplicate is typed, whether it is a number (phone number in this case) or a text string (name in my case). Both the new cell and the cell it is duplicating need to be highlighted.I've tried the countif formula but to no avail. If it matters, I'm in a French version of Sheets.
Conditional formatting of duplicate values
google spreadsheets;conditional formatting