Find Duplicates Outside of Selection/Highlight in the Same Column - Excel

[JamesStewartExcel]

Hey guys,

I want to sort a column, 

then select a section of that column, 

and then unsort the column 

and let Excel find me all duplicates throughout that column that corresponds to any of the cells I selected before and preferably select them.

In short; I need Excel to find me any duplicates of any cell inside my selection, but OUTSIDE of my selection in the same column.

Example:

(34 SELECTED)
(73 SELECTED)
23
86
234
21
73
853
34
11

OUTCOME:

(34 SELECTED)
(73 SELECTED)
23
86
234
21
(73 SELECTED)
853
(34 SELECTED)
11

Any help?

Thanks!