How do you find prior diaries on same subject

Yesterday evening I posted a diary on Lt. Gen. Helmly's memo saying that the Army Reserve is on the fast track to being irretrievably broken.

Army Reserve 'broken'

Two comments pointed me to a prior diary on this story.

Chief of Army Reserve Criticizes Policies

I had done a diary search on the word "reserve" before I posted, but the earlier diary didn't come up. And it still doesn't when I repeat the search.

Now I see that a third diary on the subject followed mine last night. It does show up when I search on the word "reserve."

Army Reserve Unable to Fulfill Duties

What is a good technique to follow to prevent duplicate diaries? Any ideas on why the first diary didn't pop up when I searched?