[tlasjr]

Depends. What if the next person who buys them price matches the TRU ad and gets the second one for less. Either way I don't think "they may not have lost money on the deal" would be a defense an attorney would let you go with.
Target expects some of that though. Thats why they limit you to two or three returns without a receipt in a rollign yea, or why they told meas a cashier a couple years back not to bother with a price check if a customer disputed a price if it was less than $20.
I'm not judging Do Boy, yeah it's technically illegal but so is downloading copy written material or playing the football card at work. If you're okay with it go with it.