KanjiJLPT N2
Duplicate

duplicate, double, compound, multiple

Mnemonic

A pilgrim in a ragged overcoat begs a sorcerer for help against the cold. The sorcerer grabs the pilgrim's overcoat, slaps it on a magic mirror—and an exact copy slides out. Now the pilgrim wears two overcoats layered up: a perfect duplicate!
Additional thoughts
Picture the pilgrim's overcoat literally splitting into two identical copies via the mirror. The layering of two overcoats reinforces the sense of multiplicity and repetition baked into the kanji.
Quick recall
A pilgrim's overcoat is magically mirrored into a perfect duplicate!

Details

The keyword for 複 is duplicate. This kanji conveys the idea of something being doubled, repeated, or existing in multiple copies. It carries the sense of complexity or multiplicity, as when something is layered or compounded rather than singular. It is used in contexts relating to reproduction, repetition, and the notion of things being plural or composite in nature.
On'yomi
ふく