The problem of Johns and Josephs

Looking at Rootsweb, "an Ancestry.com Community", for JOSEPH BRANDL, I realized that some family researchers are confused by two Brandl men with similar given names who married Janson sisters.  Both couples lived in Buckman, at least for awhile...

John A Brandl (b 1883) married Frances Janson.  Their kids were Adella, Ed, Roman (or Charlie), Leona, Alfred and Florence.  ( Adella married Killian Zenner, Ed and his wife Sadie are familiar, and Charlie had the Ford garage in Buckman when I lived there.  Mom mentioned the others, but I don't have "faces" for them).

Here's John's WWI draft card, signed by his brother, the town clerk:

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Joseph E Brandl (b 1891) married Rose Janson.  Their kids were Ervin, Marion, Leo, Armella, Bernard and Doris. (Ervin was postmaster in Buckman when I lived there, Leo became a priest, and Armella became Sr Mary Joyce, OSF).
Joe was the town clerk in 1917-1918 when all men of a certain age had to sign up for the draft (WWI).  Here's his own draft card, signed by himself:

Let's not even get into the confusion over cousins John and Joseph JANSON, the immigrants....