Shared effect memory in S3M modules appears to have broken a while ago... In the attached example module, both channels should fade out at the same rate (the H81 parameter is transferred to the K command as K81, which effectively results in a K01 command). Most famously this breaks Satellite One by Purple Motion, although in that case XMPlay currently somehow still manages to apply a volume fade (but it's way too fast), so I'm not exactly sure how this broke.