Hi, current law student here. I would advise you not to apply for all three. The requirements can be a little different for each course, with some being more selective than others, but they have a similar baseline all around. I know a few people who applied for two, i.e. the LLB and another course, but not three.
I'll just flesh out a bit more why: for KCL there is quite an emphasis placed on the LNAT MCQ, so if things didn't go amazing in that, you might find yourself with blanket rejects. Also, you might decide you don't want to go to KCL, is that a possibility? Not to mention that writing a personal statement that reaches all three might not be easy.
I don't think they'll think you don't know what you want to do, it just isn't the beat idea to put so many of your eggs in the same basket. Rejections can be arbitrary due to the amount of applications universities - not just KCL - get, especially for law.
I won't say don't apply for two, but do rethink before applying for three at the same place.