While I never had a true multiple orgasm, but if I was to turn the clock back about 25 -30 years, my refractory time would be a mere minute or two; so short I would stay semi-hard till I started again. While I never really counted how many times in a row I wanked, but more than once it would be until I was either dry or raw, whichever came first.
Nowadays, the best I've been able to achieve is to come again within a half hour minimum and for a maximum of twice, but that would require me being really, really horny as well as perhaps whatever herbal cocktail I have found is most effective. During these rare events I have always surprisingly found that while the second ejaculation is of course less, the orgasm is actually more intense.
But at this point in my life, 99.99 % percent of the time I will not have another orgasm till two days later, although less often it might be either as soon as the next day or as much as three. Unlike back in the day, the desire and ability is no longer there for anything more frequent.