There is a Milanese man called Mr Lino Ieluzzi - he looks like the late Formula One champion Mr James Hunt - who owns a local clothes shop, and his enthusiasm for double monks has infected the world. Right now they are the only style of dress shoes that can be reasonably described as fashionable, and Lino, as his acolytes know him, must be given some credit for this fact.
In general Mr Ieluzzi's eye-catching style is a bit like the wine one enjoys on holiday - enjoyable in situ, but not worth trying at home. Despite this, his appearance on street-style blogs has been influential. High on the list of his signature items, a list that also features double-breasted jackets and shirts with cut-away collars, are double-monk shoes. Mr Ieluzzi is frequently photographed wearing tan-coloured double monks with the toecaps polished in a much darker shade; the overall effect is not inconspicuous.
Personally I've only gradually come around to monk shoes, whether with single or double straps. For a long time black Oxfords were the only formal shoes I believed a man needed. Then I came to see the virtue of wearing brown leather shoes, at first with blue suits or blue jeans, and then with almost everything, because it's a far more interesting colour than black. Brown or tobacco suede brogues were the next shoes I bought, not least because they look as good with a suit as they do with a pair of jeans, but the appeal of monks still eluded me.
I now understand that the reason for my reticence is that it's not immediately clear where monk shoes sit in the pecking order of footwear formality. Such concerns were cast aside when, in a small Milanese shoe shop (SW1, which has now sadly closed), I happened upon a pair of single monks in sand-coloured suede. The thing that endeared them to me was the fact that the shoes could rarely be worn for business. At last I understood that the joy of monks is that they're not universally acceptable, and that there are environments in which they won't feel quite right, because they're not the safe choice. This is a price worth paying for clothes that are distinctive and characterful.
The difference between single and double monks comes down to attitude. Single monks are somehow softer, more understated and timeless (which is why they look so right in chocolate brown suede), while double monks are harder, crisper and arguably lend themselves better to dark brown leather. It's this attitude that, presumably, accounts for their current popularity. Double monks have a slightly military feel, thanks to the four straps, and are almost invariably designed with a toecap, although this is merely a convention.