I dont think kakashi was able to tell the water clones apart, if i remember correctly he attacked water clones more than once.
Do NOT mix the sharingan's enhancing abilities with battle experience. Kakashi is a VERY VERY VERY well experienced ninja and he apparently had already learned the Water Clone jutsu prior to meeting Zabuza, remember he's been in battle for ages.
And if i remember correctly either on the manga or anime kakashi used water clone jutsu again. In principle the clone techniques should be very very similar to each other so if u know and understand one, it shouldnt be too hard to learn and understand another if u practice it.
And the whole copy thing is Kakashi's own skill, this is NOT sharingan's ability. Sharingan gives u higher insight into DETAIL OF MOVEMENT. which complemented by a natural ability to pay attention to detail in order to copy ninjutsu, gives rise to the ONE AND ONLY COPY NINJA of konoha.
You can all say "well Sasuke was shown to be able to copy techniques too" NOT EXACTLY. Sasuke only partially copied Rock Lee's move, by analysing it with his Sharingan and then using his own skill to attempt to perform it, but as you saw Sasuke's version is different he couldnt copy the whole thing and never again are we shown Sasuke copying jutsu, nor does ANYONE other than Kakashi.
So plz ladies and gentlemen lets stop the "sharingan is able to copy ninjutsu" points because thats not what it does. Sharingan's abilities were clearly explained b4.
Same thing with the genjutsu thing, Sharingan doesnt auto perform genjutsu. You need to learn the genjutsu and then use the sharingan to enhance it.