Spalding Confusion

Researching my Spalding links in Suffolk:

Having located my ggg grandfather, John Spalding born c1826 in Fressingfield, Suffolk, I managed to establish that his parents are John Spalding and Sarah through the IGI. Further to this, I established christening records for John's (1826) siblings;

Sarah Anne in 1819
Charlotte born in 1820
Louisa in 1823
Mary Anne in 1827

In tracing their descendants, I became puzzled by other records in the IGI listing a marriage record for Charlotte Spalding in 1840 in Fressingfield, Suffolk to Robert Riches; Charlotte is shown as the daughter of James Spalding and Hannah, but her birth date is 1828 in Fressingfield.

Charlotte and Robert Riches are listed in the 1840 Census, with Charlotte's birth date being C1820. They are listed again in 1851 with their children and, interestingly, Charlotte is listed as the sister-in-law of the head of household, Benjamin Collett. Benjamin's wife is Sarah Ann.

Again, in the IGI the marriage record for Sarah Anne Spalding shows the parents as James Spalding and Hannah Rose, with her birth date as 1830 in Fressingfield. In 1851, Sarah's birth date is c1820 in Fressingfield.

I surmise that the data in the IGI is a mistake. There are matching birth records for both children as daughters of James and Hannah in the IGI also and I believe that they have mistakenly been linked to the marriages of Collett and Riches.