Check if array contains text from a list and when a value apears more then once display that value

Question

What if I have 4 columns with data, and want the value that is more than once in those 4 columns(A-B-C-D).

apple  pear  melon  grape
melon  apple melon  grape
pear   melon melon  pear

My list in column E is;

``
apple
pear
melon
grape

And what I would like is that in column F the value appears of the fruit that is more than once in a row. 
So F1 should return nothing, F2 should return "melon", and F3 should return "pear, melon"

Is that posible with a formula?

Answer 1

Try,

In B1, array ("Ctrl"+Shift"+"Enter") formula copied down :

=MID(TEXTJOIN(", ",,FILTERXML("<a>A<b>"&SUBSTITUTE(TRIM(A1)," ","</b><b>")&"</b></a>","a|a/b[not(preceding::* =.)][following::* =.]")),4,999)

Remark : If you have Office 365, the above formula is normal entry.

If source data put in separated cells, then formula become >>

In F1, array ("Ctrl"+Shift"+"Enter") formula copied down :

=MID(TEXTJOIN(", ",,FILTERXML("<a>A<b>"&TEXTJOIN("</b><b>",,A1:D1)&"</b></a>","a|a/b[not(preceding::* =.)][following::* =.]")),4,999)

Remark : If you have Office 365, the above formula is also normal entry.