"More" button in Vault ServiceWeb doesn't always work


The "more" button doesn't always work in the Vault client, like serviceweb or serviceweb2.  Sometimes it gives me the same page of results instead of a new page of results.


It seems like it happens when the number of identical results are more than the maxhits value. If there is any uniqueness to the results (for instance searching on SAM would up results containing both Samuel and Samantha) then it works. But if the search key has lots of identical results, then the "more" button doesn't work.
I think has something to do with how Vault processes chunks of searches behind the scenes and also how the indexes are set up.
Can you confirm, and remind me what needs to be done to resolve it?


UPDATED: September 18, 2017
This has to do with the way Vault clients normally page through results by specifying the key to continue a search from. If you have a large range of duplicate keys like you do in this case, it never gets past the duplicates.
Say there are 200 entries with the key "W22771467" and the max results is set to 100. The "more" will take the last key found in and start a new search that continues from there. In this case the last key is also "W22771467" and it continues the search from the *first* "W22771467" entry. This can result in never making progress.
The normal way to deal with it is to increase the size of the maxresults setting in web.xml to be larger than the worst case range of duplicates. This isn't a great solution since it can increase the overhead of all searches since it fetches more records.
<description>Maximum number of search results to display.</description>
Another way is to make the keys more unique so that large ranges of duplicates never occur in the data. This typically isn't practical for existing installations where you'd have to make bulk changes to journals and reindex data. It also depends on what unique information is available in the data. If you have a unique number, that could be appended to the key. 
In this case you may also want to look at whether member id is a document property or an account property. As a document index, this is creating an entry for every document.