Usually by accident. The glitch (not this particular version, but the glitch that makes this possible) was discovered first by Luiz Miguel when this grab accidentally happened to him during a speedrun:
(The sub tank and heart tank are collected simultaneously)
Everybody was confused for a long time until people really started to replicate the trick and understand it. And then applying the logic to other situations.
Usually by accident. The glitch (not this particular version, but the glitch that makes this possible) was discovered first by Luiz Miguel when this grab accidentally happened to him during a speedrun:
(The sub tank and heart tank are collected simultaneously)
Everybody was confused for a long time until people really started to replicate the trick and understand it. And then applying the logic to other situations.