Tegan and Sara were worried 'Heartthrob' would sound like two different bands.

The duo - made up of the titular Canadian twin sisters - were wary of how different their individual songs sounded on previous albums 'The Con' and 'Sainthood', so decided to collaborate to create a ''cohesive'' feel for their latest album.

Tegan told website Drowned In Sound: ''I was really worried about ['Heartthrob' being disjointed]. We had a meeting really early on in the writing process with the chairman of our label and one of the issues that cropped up was that I thought we were two separate bands.

''I thought we needed to be more cohesive, but he was like, 'Why?! Do whatever! Have two voices!' But really it struck me as completely counter-intuitive.

''That [process] started for me when I said I wanted Sara to write on all of my songs. She wrote on every single song, whether it was just a bridge or a melody or some lyrics, I just felt we needed more collaboration on the songs, and also that we needed to sing on all of each other's songs.''

After focusing on working together, Sara now thinks 'Heartthrob' is their most ''coherent'' album.

She added: ''With this record, we were working with different producers and different musicians, and I kept thinking, oh god - I don't want this to be one of those records where everybody's like, 'It feels like just a bunch of songs. It has no theme. It has nothing to tie it together!' And because we were focusing so much on that it's now ended up being our most cohesive and coherent record.''