I believe these men are all from the same family. They were all found in Humboldt County 1900-1930 census. They lived in Pacific, Ferndale and Table Bluff. If you can confirm that they are father and sons, or add more info to what I have, please contact me at dbjmlew@swbell.net , Thanks!
Martin MENG b. Feb 1851, DEN d. bef. 1930, Humboldt, CA. emmigrated 1880, m. abt 1873, Johanna b. Jul 1853, DEN
Children:
Andrew P. MENG b. Sep 1874, DEN m. abt 1896, CA, Hansene (Hansie) b. Dec 1876, DEN (children: Constance, Mamie, Curtis and Merton or Martin)

John P. MENG b. Jun 1876, GER or DEN m. abt 1898, Humboldt, CA, Martha b. Jul 1873, NOR or CA (children: June M., Olive G., Marvin P., Grant J.)

Johanna states in 1900 census that she has had 3 children and 3 living. I didn't find any other MENGs in the Humboldt County area, so maybe the other child was a girl or another son, left behind in Denmark or Germany.