Sci fi vintage movie about doppelgänger phenomena
You don't actually mention the doppelgänger phenomena in your actual question, so I'm not sure what you remember about it, but in Solaris the eponymous sentient water planet can manifest physical simulacra based on the cosmonauts' memories. It creates a doppelgänger based on the main character's dead wife Hari, for example.
a group of astronauts, and I remember there were three of them, but well I'm not really really sure.
The main character is Kris Kelvin, and he rendezvouses with his two colleagues Sartorius and Snaut on the Solaris space station.
They landed on a planet similar to Earth, and they see themselves in a kind of field, meadow or garden.
OK, Solaris is not really similar to Earth. It's completely covered by a sea, and can't normally be landed on, so the majority of the film takes place on a space station in orbit around the planet.
However, near the end of the film the sentient sea creates islands that can be landed on. There, it recreates the main character's memories from Earth, including a garden (and a memorable scene in a house which you might remember, inside which it eerily enough is raining) and a field/meadow.
I barely remember more, but something about these astronauts like seeing their own lives as memories or future in this planet. Don't know if one of them was seeing himself saying goodbye to his dying mother.
Kelvin, the main character, says goodbye to his father before leaving Earth, either because he is actually dying or because he's so old that he will be dead when Kelvin returns (it's not made clear which is the case); this is one of the memories he relives on Solaris.
This was a color movie, probably of the 70s.
Solaris is from 1972. Here's a trailer.