Here is a picture of what it is like...

If I click the top most 'Air Training Corps' (or the top most of the pair of same contacts) then it firstly expands the bottom set, then when you click again expands the top list. When you click the top list to close, it closes the second list in the pair and then the first.
It is a bit strange how, for example in my mates group, it has some contacts online in one group, but also a few different people online in the other.
After a bit of rearranging, I now have 2 lots of each contact. There will be an "Emily" then the same Emily again straight under, or whatever. Sometimes it is an older version of their name, other times it is updated and new.
Does anyone have any idea how this could have been caused? I can delete groups, but sign out and sign in just to find they are back again.
Cheers