What you did is flawed on multiple levels. You did two tests consecutively, and then also looked at the payout. The difficulty of the algo you mine will have changed in the meantime, making the 2nd run easier/harder to mine, but never the same. You also looked at payouts but never mention what currency, because if it is anything other than the coin you mine, and it looks like you are talking about BTC, then the market will also have fluctuated the price by the time of the 2nd run. Shortly put: don't trust what you just did ...