Wow, those paintings are absolutely gorgeous! But then, so are your dogs
. I'd be flattered that other people wanted to buy a picture of my dog, but I'm sure that whoever bought it has no idea whose dog it is or even if it was a real, live dog, you know what I mean? I'd just be sad that I couldn't buy it myself. And if they didnt' tell you that they were going to be putting it up for sale, I think I'd be a little annoyed.
I think you should ask if they could do another set for you for a set price for the two of them (not the same as what they sell for on ebay of course). I def. think you should be able to purchase paintings of your own dogs that you supplied the photos for at a decent price.