Right, so let's look at the "childhood kidding" around the name "Nikki":
Picky
Icky
Sticky
Hickey
Dickey
Flickey
Trickie
Quickie
There's no shortage of ways to ridicule the name "Nikki", and there actually may be MORE ways to ridicule that name than the name "Nimrata", which doesn't rhyme with anything and is pronounced phonetically.
So the ridicule of an unusual name (unusual for whom?), in this case Nimrata, would be along purely racist lines, wouldn't it? And because of that, Nikki (or her parents, we don't know) felt compelled to start going by "Nikki" at a young age. Why? Because of the racism you've exhibited on this thread.