The $15 upgrade fee through our payment provider (Square Pay) or the $10+ deposit with our sports affiliate partner (Underdog) is meant to be per contest, to offset the revenue the ads and popups would have generated on each individual contest.
It makes more sense from a percentage perspective, both as a benefit to you and SBPS.
For us (SBPS): Twice the contests means double the visitors. That would have meant double the page loads, and double the ad revenue.
For you (Commissioners): Twice the contests means 200 boxes to sell, or double the entry fee collected. That's double the funds raised for the cause or the fun had by friends/family.
If you think of it that way, it's less a case of you being charged for something twice, and more of a perfectly proportional cost/benefit thing, as your contest continues to produce the same percentage of revenues for prizes and fundraising.