On Aloha, to prevent additional promotions from being used, after one is already in play, ensure that the following is configured:
In Aloha, de-select all possibilities in the Comp setup. for Punchh.
To further prevent this, do the same on any and all internal Comps that may be available.
Looking at the Promotion, Restrictions, for example, these could be read differently as, " Do you want to allow a promotion while there is an existing promotion on a check/table?" To Enable this, the checkbox would need to be selected. To Disable, this would need to be de-selected.