Duplicated payment references

Hi  Users

We are working on production environment and we having the following problem:

1-when we are creating manual payment and we add a  manual reference and save the payment then we try to other using next the

system add the same reference for both payment. For example if we create a manual payment with a reference  1000 and then

do the other using next, the system does not take 1001, the system take 1000, it duplicate the reference(1000 for both the same payment method )

we realized when we put the manual reference for example 1000 it does not update the last ref number in the tab payment method in external account page.