It sounds as if your query is based on the incident escalation point table. This is why you are seeing more than one row when more escalations are created after the severity is changed and a new response level with new escalations are applied. On your test system, you could find the query within the Query and Report Designer and then you could perhaps modify the criteria to exclude those at a status of Cancelled. Escalation points that are Open will change to a status of Cancelled if a new response level is applied. The problem is that Expired (or breached) escalation points will not change to a status of Cancelled and you won't want to exclude all Expired escalation points from your query.
I wonder if your query could be re-written to be based on the incident table instead? It may depend on the version that you are running, the information you need to see on it and the order that you want it to be in.