There are so many equipment-dependent factors that can affect your performance, and I find this to be especially true of the bench press. Bench height, material (i.e., adhesiveness), thickness, the adjustability of the hooks, the presence of safety rails, bar thickness, bar knurling, whether the sleeves rotate or not, the distance between the rings, the quality and exact weight of the plates are some factors that I've noticed. I can work with some equipment and bench a "few kilos" more than when I use the calibrated Eleiko weights, Texas Power Bar and competition bench at my home gym.
Either always train bench at the same facility and simulate meet conditions as best you can (by adjusting the above variables), or find a better gym with competition plates, bars and benches. Or get used to this discrepancy and don't make too big of a deal out of it.