Curtis and Samuel Birth Dates

Curtis:
1880 Census: 7 = 1873
1900 Census: 25, July 1874
1910 Census: 33 = 1877
1920 Census: 46 = 1874
1930 Census: 54 = 1876
WWI Draft: July 17, 1873
Death Cert: Unknown on June 1, 1949
Tombstone: 7/17/1876 - 6/1/1949

Samuel:
1880 Census: 4 = 1876
1900 Census: 22, March 1878
1910 Census: 31 = 1879
1920 Census: 38 = 1882
1930 Census: Dead
WWI Draft: March 6, 1876
Death Cert: 62 (or 52?) on February 25, 1928 = 1866 (or 1876?)
Tombstone: 1876 - 1928
Yopp Funeral: 53 on February 25, 1928