There's a reason genealogists are told to utilize as many sources as possible and to get to the original when they can.
I've been working on Montevelli, the adopted son of James and Elizabeth Rampley, who lived with them in Walker Township, Hancock County, Illinois, from at least 1860 through 1880 when he appears with them in the census. In 1860 his last name is Lobb, in 1870 his last name is Harness, and in 1880 his last name is Rampley. His age changes by 10 years, which is a slight concern, but given the first name's unusual nature, I'm operating under the assumption it is the same person until information to the contrary is located.
One of the items I was working on was his marriage. FamilySearch, Ancestry.com, and the Illinois State Archives have Illinois marriage indexes online. All apparently pull from the original records--in this case from the Adams County, Illinois, courthouse. The Ancestry.com and Illinois State Archives dates agree (20 September 1881) and the FamilySearch only provides a year (1882) which is different from the other two dates.
[Click on the images for a bigger view]
What's the real date? That will have to wait until I get to the Family History Library to look at the microfilm, unless some kind soul takes pity on me and offers to look it up.
The difference is not crucial in this case. However, there are situations where differing dates could be significant.
And this situation makes the point that any index should be used as a means to get the original record.
Another reason for getting this record: Illinois marriages in the 1881-1882 era have the potential to provide names of parents--especially helpful for the apparently adopted Monteville.
