I have always thought ABBA members share many coincidences with each other. Both couples met - almost at the same time - in 1969, both Benny and Frida had two children - a boy and a girl - from previous relationships, both Frida and Agnetha had alrealdy met each other on a TV show before they met Benny and Björn, both guys didn't know to read or write music and both are musical geniuses, both of them got married for the second time with women with whom they are married till today... and so on. We may come across these and many other facts when we read their biographies or even when we collect their pictures. If you still have any doubt about it, just take a look at the pictures below and you'll know what I mean.
When I see the foursome here, for instance...
... I quickly remember them in this another photo
Notice that even ABBA members are in the same places
When I see Frida's dress here...
... I immediately remember Agnetha's in this another one
When I take a look at Frida's leg here...
... I remember the same joke in this picture...
... or in this another one
And even the same smile on Benny's face!
And when I got delighted with this lovely dance...
... I know I've already seen this another one!