Q:

Spreadsheet: Find Another Cell With The Same Value

I have a column of names; Each name has exactly 1 duplicate, Is there a function I can use to find the row number of the 2nd copy of the name.

So the values should be 2,1,4,3,6,5,7,6 and so on.
In the above example, the duplicates exist just below  each other but they could be in any order

A:

You can use this formula :
=IFERROR(MATCH(A2,A3:A$1000,0)+ROW(), MATCH(A2,A$1:A1,0)+ROW(A$1)-1)
The key is to split your data before & after current range and use absolute / relative references correctly.

