Unable to pass multiple seeding files to db:seed

Hi all,
i'm trying to execute the following command without success:
`sequelize db:seed --seed server/seeders/seed1.js, server/seeders/seed2.js --url $DB_URL`

The result is that only seed2 will be executed. 
The documentation say this: **--seed  List of seed files to run.**
Someone can explain me how to pass multiple files?

Thanks