Don't go crazy and make them wildly different or it will sound very unnatural as you cycle through them. But just shift velocities and 'rush' or 'drag' notes ever so slightly. Even the best finger drummer isn't going to lay down rock solid grooves each and every time. But when you get a good groove down, or at least, one that has a great vibe about it, you probably don't want to scrap it just because your second snare hit is a bit off the mark. Rather, you have two choices.
Event edit the sucker, or quantize the whole passage.
The word quantize has taken on a large fear factor in rhythm programming. The fact is, quantizing is often your best friend for saving you time. Quantize your mistakes first, either to a very rigid quantization grid with 0 per cent swing factor, or loosely with 5-10 per cent and then go in and make the minor adjustments. If your finger drumming skills are very poor, you might just be better off dropping flourishes and accents in by hand in an event or graphic editor. I know how difficult it is for many artists to catch the 'groove' as the sequencer cycles by.