How can I extract duplicate values from multiple columns into one single column as unique entries ?

[KnizEfl]

Hi everyone, 

Please refer attached image for context - I have 5 columns with duplicate values across all of them. I want to extract only the highlighted (in red)  duplicates into one single column ( grey highlight) as unique entries. 

What are the formulas and other methods I can use to do this? 

Thank you, 
K

[#2]

@KnizEfl Haven't even tried doing this with formulae. PowerQuery seemed to be the easiest tool to achieve what you need. See a small example attached.