IT WORKS!  I just picked up 20 bottles of Head & Shoulders – all varieties – and this is how it worked:

Each first bottle rang up at $4.49 and the second one was $2.24.  The cashier scanned the BOGO after each set of two bottles.  Coupon took off $4.49, so each set of two was $2.24.  This has a shelf tag of $6.29 at my location.

Head and Shoulders is currently on sale at Walgreens for between $3.99 and $4.49 as an August monthly deal.  Next week’s sale has them for BOGO 50%.  There is a BOGO coupon in the 8/4 rp2 which expires today, August 31.

I’ve tried it all ways and this is definitely a ymmv situation:  The coupon value goes up to $6.99, but I can’t be certain of how the register will read it until after early activation.  One thing I do know is that you cannot have the cashier run multiples (example:  8 x 1 bottle), but instead they must scan each and every bottle.