I thought the clone wars were plural because they were a number of conflicts that all kind of sprang up at once or close together due to cloning being invented or made easier somehow. Any group of systems, warlord or terrorist cell suddenly had the capability to make a clone army, and it destabilized the whole galaxy until cloning was somehow banned or prevented or all the would-be rogue cloners (what the Thrawn books call the Clone Masters) were dealt with. It would have been even more chaotic because you could use clones to impersonate people and sow confusion and paranoia.