I've tried this in jemplode 45 with no luck - was "size" a valid tag on that release? Should I try again with the latest version?

My Excel solution would be to use conditional formatting, I think - i.e. the criterion would be to see if concatenation of cell A2 +B2 = that of cell A3 + B3 (where column A = title and column B = artist) then highlight in red if true - then paste that condition down the length of the list of alphabeticallly sorted titles.