A lot of people have more than one type of seizure. It's not rare at all, and people also have changes at times, either with horomonal changes with aging, stress, etc. I have both daytime and nocturnal complex partial seizures, and I suspect autonomic seizures (vs the autonomic disorder- but not sure since the tests for the autonomic disorder were positive), or one leads into the other.
Some people have one type of seizure, and during an unusually stressful time will have generalized (GM) seizures, when they don't normally have them. Epilepsy doesn't stay static. Changes in the brain, and kindling also make some seizures more likely, and others more possible, since the electrical impulses in the brain are already on high gear. It happens