This is what I know about Laurentius (Lars) (Lauri) Piispanen...
Born 14.8.1852, Jokilaks, Kivijärvi; parents Elias Johansson Piispanen, born 16.2.1829; died 17.7.1854; and Ebba Kaisa Kahelin, born 1824; died ?
Siblings:Henrik, born 20.4.1851, died 17.10.1852; and Susanna Maria, born 3.6.1854; died 2.9.1858
Married Eva Johansdr Kinnunen, 8.6.1873, Kivijärvi.Eva Johansdr Kinnunen, born 9.6.1849, Seppälä, Heinolaks, Kivijärvi; parents Johan Henrs. Kinnunen and Anna Sofia Thomasdr Kotilainen; died 6.4.1881, Kivijärvi
Children:Werna Paulina, born 24.7.1873; Hulda Maria, born 12.5.1875; died 20.5.1876; Johan Richard, born 22.6.1877
Married Karolina Henriksdr Kinnunen, 13.11.1881, Kivijärvi,Carolina (Karolina) Henriksdr Kinnunen, born 17.10.1854, Seppälä, Heinolaks, Kivijärvi; parents Henrik Mattsson Kinnunen and Lena Hänninen; died 17.12.1896, Kivijärvi
Children:Einar, born 7.3.1882; Wilho, born 8.11.1883; Aliina Elviira, born 18.4.1886; Sylvi Maria, born 17.2.1888; Impi Johanna, born 7.11.1890
Came to Quincy, MA in 1893.
On 29.1.1898 at Fitchburg, MA, Lauri Piispanen, age 45, parents Elias and Ebba Kaisa; married Sanna Kaisa Keskinen, age 36.This was Lauri's 3rd marriage and Sanna's first.This is your Lauri Piispanen.I told you about this marriage before, but you chose not to believe it.
1910 US Census:Louis Piispanen, age 57, born Finland; wife Susan, age 52, born Finland; step-son John Larson, age 23, born Finland; residing at 6 Forest Avenue, Quincy, MA.According to the census, Louis Piispanen and wife Susan had been married for 12 years, which tracks with the 1898 marriage record.It appears as though M2 (second marriage) is shown for both.And Susan's age in the census does not track with her age shown in 1898 (36).But the census shows Susan with the name Piispanen, not Larson, which is the last name of step-son John.In spite of these inconsistencies, I would say this is your Lauri Piispanen and wife Sanna Kaisa Keskinen.There was no Louis Piispanen.John Larson must be Susan's son, either from a previous marriage; or a child born out of wedlock before she married Lauri Piispanen.
US Naturalization Records Indexes:Lauri Piispanen, born 14.8.1852, Finland; occupation:stonecutter; residence:6 Forest Avenue, Quincy, MA; name of wife:Sanna
Various Quincy Telephone Directories show Lauri Piispanen, address 6 Forest Avenue.
The 1924 Quincy Directory shows Lauri Piispanen, wife Susie, 114 Town Hill
I don't think there was any mystery...