Jane Dark Sugarhigh blog on Beyonce's "Irreplaceable" restoring "melodic range to pop"

Fair enough, but that doesn't really answer my question. I didn't ask how they are similiar, (and half of that is based on circumstance, rather than anything within the songs. the circle-of-fifths thing may be a good point, but my knowledge of music theory is rather rudimentary) I asked how one is a ripoff of the other. I don't see any reason to assume that Beyonce was consciously or even subconsciously setting out to make a song that sounds like "Unpretty".

I did not use the word "ripoff" to imply intent on the part of Beyonce. I used the word "ripoff" to imply similarity, chronology and how I view the relative quality of both (I am not a fan of "Unpretty" but I would rather listen to that any day over "Irreplaceable", despite Beyonce being a much better singer than anyone in TLC).