Why do my Clivia flower bloom twice a year (Autumn & Spring)?

dont know but lucky you. Mine only do it once a year.

Possibly because of where you live - which I can't work out from the flag, lol

Mine did flower twice this year too. In february and at the moment. I have posted photos of it. Probably they react with bud production to short periods of lower temperatures and especially drought. I fed my Clivia well with fertilizer after the first blooming. Later i did place my clivia cooler and kept her almost dry after blooming the first time. I did it not on purpose, but to make place for other plants. To my surprise, i saw a new flower spike. By the way, if you see a flower spike emerging: do not water until the spike is large enough. Otherwise it wil begin to bloom right there, between the leaves. It will have a very short stem and will look odd.
Enjoy your twice a year blooming Clivia :-)
Best greetings,

Lourdes (Netherlands)