The Celery Documentation: Periodic Tasks states that you can only have the name of the task to be executed (not a list, etc.)
You could create two different schedule entries:
CELERYBEAT_SCHEDULE = {
'every-minute_add': {
'task': 'tasks.add',
'schedule': crontab(minute='*/1'),
'args': (1,2)
},
'every-minute_multiply': {
'task': 'task.multiply',
'schedule': crontab(minute='*/1'),
'args': (3,4)
},
}