Sam Spencer was sitting at a sidewalk piano near Downtown Crossing Tuesday afternoon, playing a song by one of his favorite bands, The Lumineers, when two people started listening and recording.

As the crowd watched him tap away on the keys, performing the group's popular 2016 song "Ophelia," one of them stood next to him on the bench, bent over, and started playing along.

Not only did he play a portion of the song perfectly, he looked strangely familiar.

"I looked over at him and said to myself, 'This guy kind of looks like one of the guys from The Lumineers,'" said Spencer, 27.