Gilbert & George: The Jack Freak Pictures, White Cube, London

Insofar as anything to do with Gilbert and George can be described as natural, their recent fondness for axes of reflection is it. An axis of reflection is a line – the surface of a pond, say – that divides an object from its mirror image. Since their Tate Modern show in 2007, G&G's work has been full of them.

At first, the axes were tentative, splitting the artists' faces down the middle to leave them uncannily symmetrical; then they became more confident, dictating geometric form. Now, in Gilbert and George's biggest ever series, the Jack Freak Pictures, the axes have taken over the asylum. Walk into either branch of White Cube – the Jack Freak Pictures are so numerous and large as to fill both – and you're faced with a kaleidoscopic world where everything has its reflected anti-thing, where, as Macbeth would say, nothing is but what is not.

You can see how this might have happened. For 42 years, George Passmore and Gilbert Proesch have been reflections of each other, identical twins who, inconveniently, looked nothing alike. For all their attempts to become Gilbertandgeorge – the matching suits and ties, the finishing of each other's sentences – the pair have remained irksomely different: George tall, bald and English, Gilbert short, hirsute and Italian. Now, thanks to the miracles of computer manipulation, G&G can be, if not identical, at least identically modified – a wellspring of split-down-the-middle images, reflecting not just each other but themselves.

Part of the fascination of Gilbert and George's work – most of it, maybe – lies in this need to clone. Even before they became creatures of the computer, the pair were alike in being different: not from each other but from the rest of the world, which was a dark and anti-gilbert&georgian place. Always under siege for a deviant sexuality, they are now assailed for being white and Christian. (Their Spitalfields house has, in the past 20 years, been surrounded by brown Muslim Banglatown.) In the face of this, the pair's need to be seen as a single unit smacks of something like desperation: George&Gilbert contra mundum, safer as one than as two.

Thus, as I say, their taste for axes of reflection. Stand in either White Cubes and you'll be struck by the uses to which these are put: the Diana-of-Ephesus demons into which the boys turn themselves in Prize, say, or the female pudenda of Round Flag; the rose window of Sap; or the noseless, mouthless mutants of Celestial Equator. This last has two mirror-lines, the boys reflecting each other laterally and themselves vertically. Their doubled-up faces are like those drawings which are the same upside down as right way up. Being reduced to pairs of staring eyes, they also look vaguely as though they're wearing burkas.

This isn't coincidental. Islamic art, too, is given to axes of reflection, to symmetrical pattern and geometry. The thing that is being hidden in Hide isn't just G&G's burka'd faces but the resemblance of their image's central motif to Islamic star patterns. The picture is amenable to many readings – they could mean it as a homage to the art of their Bangladeshi neighbours, or it could (and this seems more likely) be hinting at the scariness of those neighbours' homophobic religion. As usual with G&G's work, the Jack Freak Pictures feel ominous, a warning of approaching apocalypse. And, as usual, the pair seem to relish the disaster, dressing up as a Union-Jacked dynamic duo – the Jack Freaks? – sticking out impish tongues and blowing raspberries.

One of the useful things about dualism, all those endless reflections, is that it allows for double-speak. Accuse them of trading on Islamophobia and they will say, hands on hearts, it's not so. And who'll say them nay? Among those being jeered at is us. There is nothing in the book that says art has to be nice. All the same, the Jack Freak Pictures feel unpleasantly two-faced, on several levels, none of them good. There are also just too many of them. It is barely two years since Gilbert and George's vast Tate retrospective and yet here they are with a museum-sized show of museum-sized works. They can do this because computers have made image-making so much easier; but as a result, these new pictures feel glib. Two Gilbert-and-Georges is enough. Two hundred is too many.

White Cube, London SW1 and N1 (020-7930 5373) to 22 Aug