GO ALONG to the Queen Elizabeth Hall on London's South Bank on Thursday evening and you'll see what will appear to be a very clever trick with mirrors. A beautiful young woman will be seated at a grand piano. The image of her will be reflected opposite. Only when the playing begins will it become apparent that this is not one musician but two - identical twin sisters Guher and Suher Pekinel.

This is no novelty act. When the Pekinels - Turkish-born but brought up in France - were teenagers they were invited to study in America by Rudolf Serkin; they got masters degrees from the Julliard School of Music in New York; they now play regularly with the Berlin Philharmonic, the Los Angeles Philharmonic, the Royal Concertgebouw and the English Chamber Orchestra. In the admittedly specialist field of piano duos their playing alone is enough to make them stand out.

Last week I went to visit the Pekinels at their London base and tried to spot the differences between them. Actually it's not that difficult. Suher was the talkative one. Get her on to the subject of Turkish politics and the words pour forth in the conversational equivalent of the Minute Waltz. Because although the Pekinels now inhabit the international no- man's-land that is home to the world's top musicians, they are also on a mission to promote the cause of classical music in their native homeland, and are helping to fund a new arts centre in Istanbul.

Turkey, Suher explained, was a much more culturally enlightened country than western Europeans might realise. "We have six orchestras now. But because there is so little promotion, people think it is like Iran." The Pekinels' arts centre is modelled on the Lincoln Center in New York.

In the meantime, the sisters are continuing to delight and confuse with their performances. There was the time, for example, that Suher, playing solo, won a piano competition in Italy, and the following year Guher arrived to take part in the same event. Sorry, the organisers told her, you can't appear in it more than once. It needed Guher to fetch her passport and point out the 'G' at the start of her name before they were persuaded that she really was a different person. Needless to say, she won the competition too.

The Pekinels still play separately on occasions. But as seems to be the case with identical twins they are obviously destined to a shared existence based on a mutual awareness that feels uncanny to outsiders. "Sometimes we perform back to back, just sensing how the other is reacting," Suher explained. "There is a responsibility to bring something very special to the music, not just as a duo but as twins."

Their QEH concert is followed, a week today, by one at St George's, Brandon Hill, in Bristol.