Just to be clear:
You purchased but did not pay.
Realizing you had made an error, you asked the seller to cancel the purchase.
You then bought the same item again and paid for it.
EBay is sending you Unpaid Item reminders.
It sounds as if your seller did not cancel the first purchase, and that is the one you are being dunned about.
Contact the SELLER again (I hope he is in North America and speaks English) and explain the situation. He may not realize there is a problem since he got paid for the item he sold.
He has to cancel the purchase. You can't.
If he does not speak English, try using Google Translate and sending your explanation in both languages. If nothing else it will catch his attention and give him a good laugh.
Worst case.
He doesn't cancel the first purchase.
He opens a Unpaid Item Dispute -- the reminder is not a Dispute yet.
You get an Unpaid Item Strike.
He gets his selling fees back on that item.
Provided you don't get another Strike in the next 12 months, that will be the end of it.
If you get a second Strike , or if you already have one, you will be automatically Blocked by many if not most sellers from bidding until 12 months have passed.