Why there are 2 timezones selected at +2 or +3 GMT?
If you hover over +2 GMT Timezone you may notice thats it has merged with +3 GMT. Because the timezones shift an hour ahead during the summer. +2 becomes +3. Those two timezones are the same. Hence thats why they are grouped and showing the common number.
In short: Russia does not have DST and they do not change their time. Hence, why +2 merges with +3.