You have to realize that at the WTO, there are a great many such coalitions that are formed around common interests. The Cairns Group is but one. There is also the G20, which unites the developing countries. There are all kinds of other coalitions, like the G10, that brings together the countries that are importers of agricultural commodities.
There are therefore more informal coalitions focused on a common interest. However, this does not mean that within each of these groups, countries adopt the same positions or defend the same interests as in all areas of the negotiation.