Array Formulas instead of helper columns

A little late but here is the chart solution using named ranges.
You need to fully qualify the ranges in the formula.

=IF(ISNUMBER(MATCH(ROW(Sheet1!$A$2:$A$24),SMALL(IF(Sheet1!$A$2:$A$24<>"",ROW(Sheet1!$A$2:$A$24)),ROW(INDIRECT("Sheet1!1:"& CEILING(COUNT(Sheet1!$A$2:$A$24)/2,2)))*2-1),0)),Sheet1!$A$2:$A$24,"")