You may have instances where your customer has more than one service or location with you and they want their Direct Debit payments to be made separately. You can have more than one contract set up with the same bank account details, however you must only collect the maximum collection amount from the multiple contracts to the value of one collection per customer.
For example: Customer Maximum Monthly Collection is £5000
Contract 1 collection is £3000
Contract 2 collection is £1000
This would be acceptable as adding the two collections together hasn't exceeded your payers maximum monthly collection.