This blog post describes how to extract duplicates sorted from A to Z from two different columns combined.

Filter-duplicates-from-two-columns-and-sort-from-A-to-Z

Array formula in D2:

=IF(MIN(IF((COUNTIF(List1, List1)+COUNTIF(List2, List1))*NOT(COUNTIF($D$1:D1, List1))>1, COUNTIF(List1, "<"&List1)+COUNTIF(List2, "<"&List1), MAX(COUNTIF(List2, "<"&List2)+COUNTIF(List1, "<"&List2)+1)))<MIN(IF((COUNTIF(List2, List2)+COUNTIF(List1, List2))*NOT(COUNTIF($D$1:D1, List2))>1, COUNTIF(List2, "<"&List2)+COUNTIF(List1, "<"&List2), MAX(COUNTIF(List1, "<"&List1)+COUNTIF(List2, "<"&List1)+1))), INDEX(List1, MATCH(SMALL(IF((COUNTIF(List1, List1)+COUNTIF(List2, List1))*NOT(COUNTIF($D$1:D1, List1))>1, COUNTIF(List1, "<"&List1), ""), 1), COUNTIF(List1, "<"&List1), 0)), INDEX(List2, MATCH(SMALL(IF((COUNTIF(List2, List2)+COUNTIF(List1, List2))*NOT(COUNTIF($D$1:D1, List2))>1, COUNTIF(List2, "<"&List2), ""), 1), COUNTIF(List2, "<"&List2), 0))) + CTRL + SHIFT + ENTER

copied down as far as necessary.

Named ranges
List1 (A2:A13)
List2 (B2:A14)
What is named ranges?

How to implement array formula to your workbook
Change named ranges. If your list starts at, for example, F2. Change $D$1:D1  in the above formula to F1:$F$1.

Download excel example file.
Filter duplicates from two columns and sort from A to Z.xls
(Excel 97-2003 Workbook *.xls)

Functions in this article:

IF(logical_test;[value_if:true];[value_if_false])
Checks whether a condition is met, and returns one value if TRUE, and another value if FALSE

INDEX(array,row_num,[column_num])
Returns a value or reference of the cell at the intersection of a particular row and column, in a given range

SMALL(array,k) Returns the k-th smallest row number in this data set.

NOT(logical)
Changes FALSE to TRUE or TRUE to FALSE

MATCH(lookup_value;lookup_array; [match_type]
Returns the relative position of an item in an array that matches a specified value

INDEX(array,row_num,[column_num])
Returns a value or reference of the cell at the intersection of a particular row and column, in a given range

COUNTIF(range,criteria)
Counts the number of cells within a range that meet the given condition

MIN(number1,[number2])
Returns the smallest number in a set of values. Ignores logical values and text

MAX(number1,[number2],)
Returns the largest value in a set of values. Ignores logical values and text.

This blog article is one out of six articles on the same subject.

Extract a list of duplicates from a column using array formula in excel
Extract a list of duplicates from two columns combined using array formula in excel

Extract a list of duplicates from three columns combined using array formula in excel
Extract a list of alphabetically sorted duplicates from a column in excel
Filter duplicates from two columns combined and sort from A to Z using array formula in excel
Extract duplicates from a range using excel 2007 array formula