As well as the 1840 one, there's a second one listed but this time in 1841, per
www.lancashirebmd.org.ukLancashire Birth indexes for the years: 1840
Surname Forename(s) Sub-District Registers At Mother's Maiden Name Reference
DEARDEN Charles Wuerdle and Wardle Rochdale WUW/2/317
Lancashire Birth indexes for the years: 1841
Surname Forename(s) Sub-District Registers At Mother's Maiden Name Reference
DEARDEN Charles Wuerdle and Wardle Rochdale WUW/3/59
I can see from
www.freebmd.org.uk that both the 1840 and 1841 births were in Qtr 1 of each year.
Going back to Reply#3, myluck shows that Samuel and Betty are listed on 1841 census (date of which was 6 June 1841) with a 4-month old Charles. So the Q1 1841 birth seems most likely.
Here are Samuel and Betty's marriage details from
www.familysearch.orggroom's name: Samuel Dearden
bride's name: Betty Widdup
marriage date: 28 Sep 1840
marriage place: St.Chad, Rochdale, Lancashire, England
groom's father's name: Charles Dearden
bride's father's name: George Widdup