I went into this store today and purchased 2 motion sensor lights. I only received my 20% discount on one of these lights. Can someone explain this to me?

If it was on purchase, you should have gotten 20% off. BUT there in the fine print.it has exclusions on some (many) brands. Check and make sure it wasn't 20% off one item. Good luck.

The coupons only good for your first purchase and the coupons only good for certain store merchandise

They have 2 20% coupns 1 is 20% off entire purchase and the other 1 is 20% off i item so possibly you used the 20% of a single item . I hope this helps