Need A MACRO to Remove Duplicate Name Header and Stack

Hi All,
I am trying but not getting what logic I can use. Can anyone help me on this?
I have some data with header to each data set having a name. For some Name “_M” has been suffixed. So my requirement is

1. Remove ”_M” for the names. (That’s not difficult).

2. After removal of of all”_M”, if the two name are same then they need to be shown in one stack under one name.

I want to add that the input I am using will like always that same name (for example “abc” and “abc_M”) will be stacked one below one.

Attached the input and Output needed.

Thanks in Advance,