How to find duplicates in an Excel column and rename duplicates?

Question

excel

How to find duplicates in an Excel column and rename duplicates?
Add an ending to duplicates:

.2
.3
.4

Example:

101
102
103
101
104
102

Need result:

101
102
103
101.2
104
102.2

Answer 1

You can use this formula:

Answer 2

Only macros in VBA