most brownie script owners let you opt for a 2nd submission and most of them only take partner submits. If they only allow 1 submission for each partner acct, the 2nd submit simply won't be allowed. Problem when using a submit service is if you have to pay for submits that don't go through.
Best bet is to get partner accts and know exactly how many submits these partners allow for each acct per day... before using a submit service. Then use something like Apollo's program,
TGP Wizards that rotates submit IP numbers to blast to all of your non partner status TGP's