Looks like I got all 40 points, and both items.
I didn't even consider the cheating angle. I have no idea how it selected the same pet twice (didn't give me the option TO select one, and Cutey was way down in the list, so she should not have been first up if I somehow managed to click and not notice it) so definitely won't be abusing it.
@TantrumOfDarknees you can't buy the same thing several times, it has to be 15 unique items. and i'm not sure but i think you'd have to keep count yourself, it just shows how many points you've spent
I've seen it with someone else happening too. Hasn't happened to me yet though and if it did, I would cancel one of them and have another pet join the shift. But if you do get all 40 points, please let us know.
Don't abuse the glitch though, so if you see it, change your pet, otherwise TNT might consider it cheating.
@Duma On another forum (not going to link it here), someone said TNT confirmed that particular purchase 15 unique prizes award is available through the entire plot. I can't confirm if it's true or not though.