How to insert a blank cell base on a condidition?

Hi,

I am planning to automate the following process. I have document with three columns. Column A and B are values, Column C1 is the result of =EXACT(A1,B1), C2 = '=EXACT(A2,B2)'........ C4 is the result of =EXACT(A4,B4)

A B C
1 1 TRUE
3 1 FALSE
d 3 FALSE
f d FALSE

I need to insert a blank cell in the first FALSE so column A2 above become A3 at the same time C3 become TRUE.One problem with the formula in column C is that after you sift down column A also change the formula =EXACT(A3,B3) and becomes =EXACT(A4,B3).

What I am doing now is sort column A and B and using conditional formation to find the unique value in cell B and insert a cell manually to column A but it is time consuming especially with one thousand rows to check .

King regards


Al