In a recent post on planting alchemy ingredients on TerrariaOnline there is a mention of multiplication of lava. The post states the following:
this blackened area is the "temporary" Lava multiplication wing. It can be made longer if you want to, but it works the same: put the lava near the one-block high wall, let it pour for a bit, and after pick it back. In contrast with the water multiplication, you need to wait a bit, whereas waiting when multiplicating water, will result in a slow water-generating process.
This seems to indicate that there is a way to duplicate lava and water somehow. The instructions above seem to require some familiarity with that feature already, or at least they are not entirely clear to me.
Is there a way to duplicate lava and water in Terraria? If yes, how can it be performed?