ונתת שמה מים
ויתן שמה מים
ונתת שם מים
All three of the above פסוקים refer to the setting up of the כיור. The simple question is: What is the difference between שם and שמה?
As the comments below indicate, there doesn't seem to be any difference between the two. But this is always what I ask when I encounter things like this: "If there's a difference - what is it? If there's no difference - why are they different?"