Which IDE and version of VA are you using?
Using the very simple test code:
int nLocalOne;
int32_t nLocalTwo;
nLocalTwo = 4;
nLocalTwo = nLocalOne + 2;
both variables are being shown in bold by VA, they have the same colour, and all references to both are correctly highlighted when placing the caret into the variable name.
I am testing VS2010 with VA 1936