Fabio spent the season on loan at QPR, who were relegated as Rafael picked up the Barclays Premier League title with the Reds.
It was a difficult experience for Fabio but his twin admits the rare time they spent apart benefitted his relationships at United.
"When my brother went to QPR, people around the club behaved in a different way towards me," Rafael said.
"Before they tended not to talk that much. Maybe they felt intimidated because we were always together. Last year they started to talk to me. It was different. It helped me a lot."
The pair are reunited now but realise one day they may have to separate permanently.
"When we first came to Manchester we said it was brilliant but we knew it wouldn't last forever and that one day we will have to play in different places," said Fabio.
"It is not made easier because we play in the same position. Unless I play on the left we can't play at the same time. That is always going to create a problem."
Rafael added: "Gary and Phil Neville did it. They played together at Manchester United for a long time but then Phil left and went to play for Everton."