duplicate names not showing (1 Viewer)

Hi I received some good help from this site back in the summer when i was landed with having to create a database for use at work. We have been using it with no trouble for a few months now but earlier today I noticed that when I used the filter by form option in the advanced part of the sort/filter ribbon for one of our workers who has the same name as another worker, it only came up with one result when I applied the filter. Is there any way that I can ensure that all workers with that particular name will come up?