Both options require at least 4 speakers (2 front + 2 back)
4 channels: map each Paula channel to one speaker. Useless unless you want to wav record each channel separately. (instead of normal 2+2)
cloned stereo: clone front channels to back channels.
Neither emulates it "better", it depends what you prefer and how you would connect your real Amiga audio output (crappy multimedia speakers? stereo amplifier? home theater amplifier? I don't think you had those in early 1990s
)