i want to keep the entries with the most dublicates and delete the rest, is this possible?

for example:

input:

column1 - column2

entry1 - entry2
entry1 - entry3
entry1 - entry3
entry4 - entry5
entry4 - entry6
entry4 - entry6
...
..
.

entry1 and entry3 reduce to one row and relete entry2

output:

entry1 - entry3
entry4 - entry6
..
.