PS3 sales tracking almost exactly 360 sales.

[ihatejunkmail0]

I'm sure almost all of you have seen this: 

http://vgchartz.com/hwcomps.php?cons1=Wii&reg1=All&cons2=PS3&reg2=All&cons3=X360&reg3=All&align=1

When the launch dates are aligned, the PS3 sales numbers match exactly the historical performace of the 360.

Is it just me, or does it seem like a really interesting coincidence that these sales numbers are tracking eachother so precisely. There seems to be way too many variables for this to be a random occurance -- it has been within a few percent for about 20 weeks now.

Does anyone have any insight as to why the PS3 sales are following exactly the same curve as the 360 sales?