[Pharo-project] Bug in Pharo compiler?

Hi All, Currently im running the Redline Smalltalk compiler (http://redline.st) over the Pharo source to make sure that it is compatible with Pharo. What I noticed while compiling the class BitBlt is that an instance variable is also used as a method argument name! If you try and do this with the environment you get a "name already defined" error, yet it is in the source. Not sure what to do about it? Rgs, James.