[RegEx] [Notepad++] Delete all similar 1st 3 characters string lines

Hello guys!

I am trying to delete lines with similar first 3 characters using RegEx

I figured out this:

((?<=\n)|^)([^\n]{3})([^\n]\n)(.\n)?\2[^\n]*($|\n)

However, it marks only 1 duplicate.

How to let it mark all the other duplicates?

Can somebody please fix the RegEx?

Thanks in advance!

Regards,
addas

A good example would be if I have these text:

Code:

abcd
abce
abcg
ebgf
ebsf

I should select "abcd" "abce" "abcg" and mark them and delete them not only the first instance "abcd"