Multiple Configuration on Dropdown Fields that are shared on Custom Forms

We would love to have the capability to use the same field on multiple custom forms but be able to configure it differently on each form. For example, we have a Brands field that contains a dropdown with all of our brands. We'd like to use this on a custom form where the user selects 1 brand from the dropdown, but we'd like to use this field on another custom form for a completely separate report, but be able to select multiple brands. We do not want to have to maintain 2 fields with the same data since that would cause extra work.