There are at least two bands sharing this name.
1. Sweethearts is s a Danish band which has achieved great success with their interpretations of classic Danish party songs. They are known as a killer live act with actress Pernille Højmark as the band's lead singer brining amazing energy and personality to their live shows.
2. Sweethearts are a motown girls high school band from Geelong, Victoria in Australia. They have toured worldwide and received recognition from various festivals around the world. Read more on Last.fm