These are the tombstones of two infant sons of J. & M. Bollenbacher, located in row 10 of Kessler Cemetery, Liberty Township, Mercer County, Ohio.
The markers are inscribed:
J. & M.
J. & M.
Died Oct. 2
Although I cannot be certain, these are likely two sons of Jacob (1848-1929) and Margaret (Huffman) Bollenbacher (1855-1921), of Adams County, Indiana.
The boys were very likely brothers and the tombstones are nearly identical. Their births would have occurred during Margaret’s childbearing years.
According to both the 1900 and 1910 censuses Margaret had given birth to eight children. Five of their children were living in 1900 and four were living in 1910. [Their daughter Dora C. died in 1902.] These two infant boys could account for two of their three unknown deceased children. Their five living children were named in the 1900 census as August William, Dora C, Jesse Charles, Abraham, and Rosa C.  
If these two boys were Jacob and Margaret’s children, one of their children would still be unaccounted for.
Margaret (Huffman) Bollenbacher died in 1921 and Jacob Bollenbacher died in 1929. They share a tombstone and are buried nearby, in row 8 of Kessler Cemetery. Their daughter Dora C. (Bollenbacher) Anspaugh is also buried there and her tombstone is in row 9, the next row east of her infant brother’s markers.
 1900 U.S. Census, Jefferson, Adams, Indiana, ED 4, p.6A, dwelling 104, household 104, Jacob Bullenbacher; Ancestry.com; FHL microfilm 1240357, NARA microfilm T623, roll 357.
 1910 U.S. Census, Jefferson, Adams, Indiana, ED 4, p.2A, dwelling & family 29, Jacob Bollenbacher; Ancestry.com; FHL microfilm 1374351, NARA microfilm T624, roll 338.