A South African friend who was a member of one of the first African hip hop groups to tour Europe, once told me that critics were really expecting them to incorporate a certain degree of traditional sounds (samples), dress (on stage and in videos) and dancing. If they failed to do so, they were often dismissed as copycats!-- Juma4, from the article Modern African music and the wall of exotism on Africanhiphop.com (h/t Wayne)
The complaint against western music critics pushing, as it were, tradition onto African performers is a familiar and reasonable one, but there's something about the wording in the quote above that gets to me. Because I think a lot of us, even the most progressive, still have a problem with the concept of the copycat. However much we've deconstructed the contradictory concept of the authentic and nuanced the idea of cultural imperialism there's still a distinct tendency, one that I've displayed myself, to cling steadfastly to the aesthetic value of originality. We may have left axiomatic and traditional values behind, but we're still holding onto our neo-modernism.
In a world of fractured genre divisions this desired originality, often as not, is not the originality of the individual but of the scene, group or culture. So in Africa we happily accept kuduro and the aging kwaito, both of which have messed with foreign formulas, but generally turn a blind eye to equally popular and modern but much more US- or Jamaica-faithful genres like Nigerian hip-hop or Ugandan dancehall. The scene as a whole has to be interestingly different from all others for us to readily accept it. (This applies within the continent too - when did you last hear any Namibian kwaito, an extremely popular and successful offshoot?)

1) The idea of the culture as a homogenous entity is suspect and the resultant values are often muddled and hypocritical. It's really interesting to look at what is accepted as being "within a culture" (and therefore acceptable as continued development) and what's considered copying. Something as vast and varied as African-American culture is often looked at monolithically and as an almost essentialist entity, where blacks are considered as having a certain tradition and way of making music to live up to. A strain of music that starts off in Miami can unproblematically be transported to Seattle, 4500 km away, but should they cross the Florida straights into the Caribbean it's suddenly copycat music. There are related ideas of selling out, proper diasporadic music and so on that can be equally mixed-up.
2) Does it really matter? Maybe we should start assessing individual pieces of music outside context. Or assess them from other criteria than originality. Or assess them out of their value within a culture. Or perhaps, honestly, not assess them at all.
3) There might be a difference you are as yet not able to hear. The old axiom that rock "all sounds the same" to the jazz musician and vice versa holds true - you might just not be onto the difference yet, so give the supposed copycat another chance. The first time I heard bongo flava I thought it sounded just like American hip-hop, but over time I've managed to pick up the differences in rhythm, mixing and harmony that make the style unique.
4) Things will change. Music is not static and does not readily form into singular structures. If you keep following a scene it will inevitably develop its own quirks if that's what you're after. For one, the idea of the "copycat" resonates within communities too, and there's a strong push to express identity through music. But even if conscious modification is not present, music always splits off and evolves as musicians grow tired of old sounds and "misuse" influences. The whole Jamaican music industry with its incredible vibrancy started off as a copycat of southern US R&B, but quickly evolved and changed. Baile funk was as late as the mid-nineties basically Miami bass. Leave the copycats alone, they can often surprise you eventually.