If you need a list of distinct/unique items from the range (column A) where items appear more than once, select a range of the same size (column C) and enter this as an array formula (press CTRL+SHIFT+ENTER):

=IFERROR(INDEX(Data,SMALL(IF(MATCH(Data,Data,0)=ROW(INDIRECT("1:" & ROWS(Data))),MATCH(Data,Data,0),""),ROW(INDIRECT("1:" & ROWS(Data))))),"")

Where "Data" is a named range containing original list (column A).

Named range is not mandatory, but I recommend you create it, so formula is easier to handle.

Note that formula will not work if any cell in "Data" range is blank.

Check example file attached.