In my experience, when conditions are right, it's normal for them to repeatedly produce eggs. The only time I kept detailed records of their breeding activity was in 1986 when I recorded that a trio of frogs (1 male; 2 females) produced eggs on eight occasions between 29 September 1986 and 29 October 1986. At that time I induced them to breed by keeping them in a tank whose water depth did not exceed 10cm (4 inches). To stop them breeding I raised the water level above 20cm (8 inches). However, although it's normal for them to continue producing eggs once they start it's not desirable to let it continue because it can weaken the females.
There are several ways to get around the problem without the expense of getting another tank. As has already been suggested, you could provide more shelters for the female to seek refuge from the male if he continues harassing her. A method I've used in the past is to get small plastic plantpot saucers and cut two or three gaps in the sides of about 1.5cm (½ an inch approx.) then place them upside down in the tank with a pebble on top of each one to weigh it down.
Another simple method is to use an inert material like a sheet of glass or plastic (e.g.: a square food container lid) to divide the tank into two sections with a frog in each section. You could also immerse a small plastic container in your tank so that you have a tank within a tank and put one of the frogs in it but that might be more stressful for the relocated frog.
You've asked about the normal mating cycle. Hymenochirus frogs, unlike most Xenopus species, originate from tropical regions of Africa with fairly constant climatic conditions which means that they will breed at any time of the year providing conditions are right (such as fresh rainfall and abundance of food). You are clearly providing them with ideal conditions, which is to your credit as many people seem to struggle trying to keep them alive (although I suspect that might be largely due to animals that were inherently unhealthy when first acquired).
For anyone with a serious interest in these frogs the best document to read is: "On the behavior and breeding biology of the African pipid frog: Hymenochirus boettgeri" by George B. Rabb & Mary S. Rabb (1963). Zeitschrift für Tierpsychologie, 20(2), 215-241. 1963