It might or it might not, depending upon the font, the size, and which version of ClearType is in use (and which application settings are applied for rendering). Microsoft's explanation of ClearType gets into this somewhat, and even shows an example where you can observe a case where two instances of a character do not render the same (see 'elle', on the right; both the 'e' and 'l' render differently in the second instance). This has to do with the use of fractional advance widths, which get resolved to the nearest 1/64th of a pixel. Thus you could potentially end up with many different instances of a single character (though as you can see, the differences are fairly subtle).
In short: I would not write anything that depends on any two instances of a character ending up exactly the same. They will be pretty similar, but not identical.