Concatenate Distinct duplicating text values

[kfeng86]

I am using concatenate distinct to rollup all the related contact names into a text field onto the account. However, every time I edit a contact record, it tacks the name (whether changed or not) at the end of the aggregate result field (on the account) without the concatenate delimiter. If I manually click to re-calculate, it overwrites with distinct values again. But I don't know how to prevent my editing of a contact to put the same name into the rollup field. Goal: get a list of all contact names on the account record, without duplicating names even when I update a contact record.

My solve has been to make this a scheduled calculate so it overwrites with distinct values at least once an hour.

Any other ideas?