If you are using the Data page as source, then in the post load processing activity , you can use "removeDuplicatesFromList" function or in the RD you can select "Remove duplicate rows" option on Query tab.
Also try this alternate approach ,create a separate page list for each autocomplete to get rid of this issue. Because if you have all 6 values for autocomplete on single data page, and it is already unique as per key, its not possible to make it unique for other 5 properties without creating separate lists.
If you are populating those values by using a pagelist via activity use when condition with builtin Pega function pzremoveduplicatefromlistpage. It takes 3 parameters as input(pagename, pageclass name, property on which you want to remove the duplicates).
First copy those autocomplete values into a temppage and then while moving into the actual page try to use a when condition to remove the duplicates before saving them into the actual autocomplete field.