A sample limit can be defined at different levels for a given product. One of the levels is Account.
However, the existing Sample Limit for an Account is not applied when a new user disburses Samples to the same Account in CRM. The Limit value on the Call Sampling page does not match the Remaining Quantity of Sample Limit.
The new user does not have access to the existing Sample Limit record.
Be sure the new user has access to the existing Sample Limit record.
CRM Help Documentation: Sample Limits