I don't care about Karlovic and if he's in game or not but according to me it is wrong to say that Karlovic is a clone of Isner. Karlovic's net skills are way better then Isner's and Isner's forehand is way better than Karlovic's, for instance. Isner' second serve is probably the best second serve on tour (but I know that we don't have any "2nd serve" ability in players profile so that ability could not be developed anyway) and, even if both players are not great runners, Isner's foot-play has improved a lot throughout the years while Karlovic's hasn't. Karlovic is a serve and volley player, Isner isn't.
The only thing they have in common is height and MAYBE serve (just the first serve anyway, second serve is completely different). Even Karlovic' slice is way better than Isner's but here, just like second serve, we dont have a skill for "slice" so that would not have made any difference anyway.
Just saying
