I'm getting much worse at keeping faces apart. If there are some similar facial features I will most likely think it's the same person. That can be quite emberassing as for example I was telling a friend I liked Going Postal regardless of the fact that Andy Serkis starred in it. With great surprised I had to learn that that wasn't Serkis in the lead, but the actor Richard Coyle. Once you know the difference it isn't difficult to tell them apart but it sure got me fooled. Seeing them next to each other you immediately focus on the differences and not on the similarities. Just as a reference, Andy Serkis on the left Richard Coyle on the right.
I had this problem before when I was convinced that actor Patrick Wymark was the same person as the actor Jay Garner. Actually I still have trouble keeping them apart. And their voices don't help because they even sound more alike than they look alike.
Now that you can see them side by side you can also see why the faces might be mistaken for each other if you only focus on the fact that some features are identical. Look at the eyebrows and nose of the two actors in the lower image, virtually identical. Now with older men it's always trickier because they tend to look more alike, but still.