There is no indication in the text that this is a different group. After giving the promise of Revelation 3:4, the Lord adds the words of Revelation 3:5 in order to stress the responsibility of the saints of Sardis to heed Jesus’ five commands, and so ensure that they are eagerly watchful for the Saviour’s return.
5 The one who conquers will be clothed thus in white garments, and I will never blot his name out of the book of life. I will confess his name before my Father and before his angels.