I'm building an alien world for a game mod, and want to avoid any blatant mistakes from a world-building perspective. The world has three moons visible in the night sky - two on one side near each other, while the third is on the opposite horizon. When viewed from the equator (my main landmass is tropical), the pair is located in the northwestern sky and the single is to the southeast. The pair are roughly both a little larger and a little smaller than Earth's moon, while the single is medium - say the same size as Earth's moon.
What affect, if any, would this arrangement have on the formation of landmasses and/or oceans on the planet? I'm currently using Earth-type erosion to form both topographies, but is this the correct approach?
Also, as a result I'm keeping the nights fairly well-lit instead of dark, similar to dusk but with a slight purplish tint. Would this affect the growth of flora or fauna to any significant degree?
I hadn't really put much thought into the details, but let's assume for this question that the paired moons are locked together and all three bodies are roughly the same distance as Earth > Luna with around the same rotation period. Under these assumptions, we can also assume that the pair would have a larger accumulative mass than the single on the other side, and that they would always be more-or-less opposite of each other throughout the year.