Here are the data. As you can see, there are about 17% of men who have a very large number of partners (compared to 3% of women). These prodigious men are obviously having sex with women who are less active.
It is clear that there is a small group of men (about 15%) who are having sex with multiple partners from a significantly larger group of women. I suspect that this is a function of evolution... but it certainly has a social impact on how mating works in modern society.
Of course, there are also economic implications...
(Digging into the data, there is a weird little spike of men who claim to have had more than 50 partners. This is not a smooth distribution, 3% of men claim to have had 50 partners compared to less than a tenth of a percent of men claiming to have had 40. The corresponding spike for females is less than 0.25% percent. This should be interesting to any math nerds reading... )